C i 1 C b C d----- = --- = ----- = ------; then C B = n.C b (5)C I n C B C D
CD = n.C d; (6)
and, consequently, the position of the needles which are found at A and B are determined.
12. The question treated in § 10, then, is simply solved. In fact, on describing the circumference C b i a with any radius whatever, I shall have
C Bn = -----; (7)c b
and, consequently,
C I = n.C i (8)
13. As may be seen, the instrument composed of three firmly united rulers is the simplest of all and easy to use. Any one can construct it for himself with a piece of cardboard, and give the angle 2 α the value that he thinks most suitable for each application. The greater 2 α is, the shorter is the distance at which we should put the needles for a given point of meeting.
14 The jointed instrument may be constructed as shown in Figs 8, 9, and 10. The three pieces, A. B, and C, united by a pivot, O, in which there is a small hole, are of brass or other metal. Rulers may be easily procured of any length whatever. The instrument is Y-shaped. In the particular case in which α = 180° it becomes T-shaped, and serves to draw parallel lines.
Fig. 8, Fig. 9, Fig. 10
Fig. 8, Fig. 9, Fig. 10
15. The instrument may be used likewise, as we have seen, to draw arcs of circles of the diameter C I or of the radius A O = r, whose center o falls outside the paper. The pencil will be rested on C. We may operate as follows (Fig. 2): Being given the direction of the radii A O and B O, or, what amounts to the same thing, the tangents to the curve at the given points, A and B to be united, we draw the line A D and raise at its center the perpendicular D C, which, prolonged, passes necessarily through the center. It is necessary to calculate the length C D.
We shall have
CD (2r - CD) = \overline{AD^2}.\overline{CD^2} - 2r.CD + \overline{AD^2} = o.
CD = r ± \sqrt{r^2 - \overline{AD^2}}.
It is evident that the lower sign alone suits our case, for d < r; consequently,
CD = r - \sqrt{r^2 - \overline{AD^2}}.(9)
Having obtained C, we put the instrument in the direction A B C. Then each point of C F describes a circumference of the same center o.
16. If the distance of the points A and B were too great, then it would be easy to determine a series of points belonging to the arc of circumference sought (Fig. 4).
Being given C, the direction C I, and C I = R, on C I I lay off C E = d, draw A E B perpendicularly, and calculate C A or A E. I shall have
d = (R - d) = \overline{AE^2};
or, as absolute value,
AE = \sqrt{d (R-d)}(10)
The instrument being arranged according to A C B, I prolong C B and take B C' = B C, when C' will be one of the points sought. It will be readily understood how, by repeating the above operations, but by varying the value of d, we obtain the other intermediate points, and how we may continue the operation to the right of C' with the process pointed out.
17. If the three rulers were three arcs of a large circle of a sphere, the instrument might serve for drawing the meridians on such sphere.
18. If we imagine, instead of three axes placed in one plane and converging at one point, a system of four axes also converging in one point, but situated in any manner whatever in space, and if we rest three of them against three fixed points, we shall be able to solve in space problems analogous to those that have just been solved in a plane. If we had, for example, to draw a spherical vault whose center was inaccessible, we might adopt the same method.--Le Génie Civil.
[Footnote: A paper read before the Franklin Institute.]
In order to properly understand the requirements of an effective feed-water purifier, it will be necessary to understand something of the character of the impurities of natural waters used for feeding boilers, and of the manner in which they become troublesome in causing incrustation or scale, as it is commonly called, in steam boilers. All natural waters are known to contain more or less mineral matter, partly held in solution and partly in mechanical suspension. These mineral impurities are derived by contact of the water with the earth's surface, and by percolation through its soil and rocks. The substances taken up in solution by this process consist chiefly of the carbonates and sulphates of lime and magnesia, and the chloride of sodium. The materials carried in mechanical suspension are clay, sand, and vegetable matter. There are many other saline ingredients in various natural waters, but they exist in such minute quantities, and are generally so very soluble, that their presence may safely be ignored in treating of the utility of boiler waters.
Of the above named salts, the carbonates of lime and magnesia are soluble only when the water contains free carbonic acid.
Our American rivers contain from 2 to 6 grains of saline matter to the gallon in solution, and a varying quantity--generally exceeding 10 grains to the gallon--in mechanical suspension. The waters of wells and springs hold a smaller quantity in suspension, but generally carry a larger percentage of dissolved salts in solution, varying from 10 to 650 grains to the gallon.
When waters containing the carbonates of lime and magnesia in solution are boiled, the carbonic acid is driven off, and the salts, deprived of their solvent, are rapidly precipitated in fine crystalline particles, which adhere tenaciously to whatever surface they fall upon. With respect to the sulphate of lime, the case is different. It is at best only sparingly soluble in water, one part (by weight) of the salt requiring nearly 500 parts of water to dissolve it. As the water evaporates in the boiler, however, a point is soon reached where supersaturation occurs, as the water freshly fed into it constantly brings fresh accessions of the salt; and when this point is reached, the sulphate of lime is precipitated in the same form and with the same tenaciously adherent quality as the carbonates. There is, however, a peculiar property possessed by this salt which facilitates its precipitation, namely, that its solubility in water diminishes as the temperature rises. This fact is of special interest, since, if properly taken advantage of, it is possible to effect its almost complete removal from the feed-water of boilers,
There is little difference in the solubility of the sulphate of lime until the temperature has risen somewhat above 212° Fahr., when it rapidly diminishes, and finally, at nearly 300°, all of this salt, held in solution at lower temperatures, will be precipitated when the temperature has risen to that point. The following table[1] represents the solubility of sulphate of lime in sea water at different temperatures:
Temperature. Percentage Sulph.Fahr. Lime held in Solution.217° 0.500219° 0.477221° 0.432227° 0.395232° 0.355236° 0.310240° 0.267245° 0.226250° 0.183255° 0.140261° 0.097266° 0.060271° 0.023290° 0.000
[Footnote 1:VideBurgh, "Modern Marine Engineering," page 176et seq.M. Cousté,Annales des MinesV 69.Recherches sur Vincrustation des Chaudières a vapour. Mr. Hugh Lee Pattison, of Newcastle-on-Tyne, at the meeting of the Institute of Mechanical Engineers of Great Britain, in August, 1880, remarked on this subject that "The solubility of sulphate of lime in water diminishes as the temperature rises. At ordinary temperatures pure water dissolves about 150 grains of sulphate of lime per gallon; but at a temperature of 250° Fahr., at which the pressure of steam is equal to about 2 atmospheres, only about 40 grains per gallon are held in solution. At a pressure of 3 atmospheres, and temperature of 302° Fahr., it is practically insoluble. The point of maximum solubility is about 95° Fahr. The presence of magnesium chloride, or of calcium chloride, in water, diminishes its power of dissolving sulphate of lime, while the presence of sodium chloride increases that power. As an instance of the latter fact, we find a boiler works much cleaner which is fed alternately with fresh water and with brackish water pumped from the Tyne when the tide is high than one which is fed with fresh water constantly."]
These figures hold substantially for fresh as well as for sea water, for the sulphate of lime becomes wholly insoluble in sea water, or in soft water, at temperatures comprised between 280° and 300° Fahr.
It appears from this that it is simply necessary to heat water up to a temperature of 250° in order to effect the precipitation of four fifths of the sulphate of lime it may have contained, or to the temperature of 290° in order to precipitate it entirely. The bearing of these facts on the purification of feed-waters will appear further on. The explanation offered to account for the gradually increasing insolubility of sulphate of lime on heating, is, that the hydrate, in which condition it exists in solution, is partially decomposed, anhydrous calcic sulphate being formed, the dehydration becoming more and more complete as the temperature rises. Sulphate of magnesia, chloride of sodium (common salt), and all the other more soluble salts contained in natural waters are likewise precipitated by the process of supersaturation, but owing to their extreme solubility their precipitation will never be effected in boilers; all mechanically suspended matter tends naturally to subside.
Where water containing such mineral and suspended matter is fed to a steam boiler, there results a combined deposit, of which the carbonate of lime usually forms the greater part, and which remains more or less firmly adherent to the inner surfaces of the boiler, undisturbed by the force of the boiling currents. Gradually accumulating, it becomes harder and thicker, and, if permitted to accumulate, may at length attain such thickness as to prevent the proper heating of the water by any fire that may be maintained in the furnace. Dr. Joseph G. Rogers, who has made boiler waters and incrustations a subject of careful study, declares that the high heats necessary to heat water through thick scale will sometimes actually convert the scale into a species of glass, by combining the sand, mechanically separated, with the alkaline salts. The same authority has carefully estimated the non-conducting properties of such boiler incrustations. On this point he remarks that the evil effects of the scale are due to the fact that it is relatively a nonconductor of heat. As compared with iron, its conducting power is as 1 to 37½, consequently more fuel is required to heat water in an incrusted boiler than in the same boiler if clean. Rogers estimates that a scale 1-16th of an inch thick will require the extra expenditure of 15 per cent. more fuel, and this ratio increases as the scale grows thicker. Thus, when it is one-quarter of an inch thick, 60 per cent. more fuel is needed; one-half inch, 112 per cent. more fuel, and so on.
Rogers very forcibly shows the evil consequences to the boiler from the excessive heating required to raise steam in a badly incrusted boiler, by the following illustration: To raise steam to a pressure of 90 pounds the water must be heated to about 320° Fahr. In a clean boiler of one-quarter inch iron this may be done by heating the external surface of the shell to about 325° Fahr. If, now, one-half an inch of scale intervenes between the boiler shell and the water, such is its quality of resisting the passage of heat that it will be necessary to heat the fire surface to about 700°, almost to a low red heat, to effect the same result. Now, the higher the temperature at which iron is kept the more rapidly it oxidizes, and at any heat above 600° it very soon becomes granular and brittle, and is liable to bulge, crack, or otherwise give way to the internal pressure. This condition predisposes the boiler to explosion and makes expensive repairs necessary. The presence of such scale, also, renders more difficult the raising, maintaining, and lowering of steam.
The nature of incrustation and the evils resulting therefrom having been stated, it now remains to consider the methods that have been devised to overcome them. These methods naturally resolve themselves into two kinds, chemical and mechanical. The chemical method has two modifications; in one the design is to purify the water in large tanks or reservoirs, by the addition of certain substances which shall precipitate all the scale-forming ingredients before the water is fed into the boiler; in the other the chemical agent is fed into the boiler from time to time, and the object is to effect the precipitation of the saline matter in such a manner that it will not form solid masses of adherent scale. Where chemical methods of purification are resorted to, the latter plan is generally followed as being the least troublesome. Of the many substances used for this purpose, however, some are measurably successful; the majority of them are unsatisfactory or objectionable.
The mechanical methods are also very various. Picking, scraping, cleaning, etc., are very generally resorted to, but the scale is so tenacious that this only partially succeeds, and, as it necessitates stoppage of work, it is wasteful. In addition to this plan, a great variety of mechanical contrivances for heating and purifying the feed-water, by separating and intercepting the saline matter on its passage through the apparatus, have been devised. Many of these are of great utility and have come into very general use. In the Western States especially, where the water in most localities is heavily charged with lime, these mechanical purifiers have become quite indispensable wherever steam users are alive to the necessity of generating steam with economy.
Most of these appliances, however, only partly fulfill their intended purposes. They consist essentially of a chamber through which the feed-water is passed, and in which it is heated almost to the boiling point by exhaust steam from the engine. According to the temperature to which the water is heated in this chamber, and the length of time required for its passage through the chamber, the carbonates are more or less completely precipitated, as likewise the matter held in mechanical suspension. The precipitated matter subsides on shelves or elsewhere in the chamber, from which it is removed from time to time. The sulphate of lime, however, and the other soluble salts, and in some cases also a portion of the carbonates that were not precipitated during the brief time of passage through the heater, are passed on into the boiler.
Appreciating this insufficiency of existing feed-water purifiers to effectually remove these dangerous saline impurities, the writer in designing the feed-water heater now to be described paid special attention to the separation of all matters, soluble and insoluble; and he has succeeded in passing the water to the boilers quite free from any substance which would cause scaling or coherent deposit. His attention was called more particularly to the necessity of extreme care in this respect, through the great annoyance suffered by steam users in the Central and Western States, where the water is heavily charged with lime. Very simple and even primitive boilers are here used; the most necessary consideration being handiness in cleaning, and not the highest evaporative efficiency. These boilers are therefore very wasteful, only evaporating, when covered with lime scale, from two to three pounds of water with one pound of the best coal, and requiring cleansing once a week at the very least. The writer's interest being aroused, he determined, if possible, to remedy these inconveniences, and accordingly he made a careful study of the subject, and examined all the heaters then in the market. He found them all, without exception, insufficient to free the feed-water from the most dangerous of impurities, namely, the sulphate and the carbonate of lime.
Taking the foregoing facts, well known to chemists and engineers, as the basis of his operations, the writer perceived that all substances likely to give trouble by deposition would be precipitated at a temperature of about 250° F.
His plan was, therefore, to make a feed-water heater in which the water could be raised to that temperature before entering the boiler. Now, by using the heat from the exhaust steam the water may be raised to between 208° and 212° F. It has yet to be raised to 250° F.; and for this purpose the writer saw at once the advantage that would be attained by using a coil of live steam from the boiler. This device does not cause any loss of steam, except the small loss due to radiation, since the water in any case would have to be heated up to the temperature of the steam on entering the boiler. By adopting this method, the chemical precipitation, which would otherwise occur in the boiler, takes place in the heater; and it is only necessary now to provide a filter, which shall prevent anything passing that can possibly cause scale.
Having explained as briefly as possible the principles on which the system is founded, the writer will now describe the details of the heater itself.
In Figs. 1 and 2 are shown an elevation and a vertical section of the heater. The cast-iron base, A, is divided into two parts by the diaphragm, B. The exhaust steam enters at C, passes up the larger tubes, D, which are fastened into the upper shell of the casting, returns by the smaller tubes, E, which are inside the others, and passes away by the passage, F. The inner tube only serves for discharge. It will be seen at once that this arrangement, while securing great heating surface in a small space, at the same time leaves freedom for expansion and contraction, without producing strains. The free area for passage of steam is arranged to be one and a half times that of the exhaust pipe, so that there is no possible danger of back pressure. The wrought iron shell, G, connecting the stand, A, with the dome, H, is made strong enough to withstand the full boiler pressure. An ordinary casing, J, of wood or other material prevents loss by radiation of heat. The cold water from the pump passes into the heater through the injector arrangement, K, and coming in contact with the tubes, D, is heated; it then rises to the coil, L, which is supplied with steam from the boiler, and thus becomes further heated, attaining there a temperature of from 250° to 270° F., according to the pressure in the boiler. This high temperature causes the separation of the dissolved salts; and on the way to the boiler the water passes through the filter, M, becoming thereby freed from all precipitated matter before passing away to the boiler at N. The purpose of the injector, K, and the pipe passing from O to K, is to cause a continual passage of air or steam from the upper part of the dome to the lower part of the heater, so that any precipitate carried up in froth may be again returned to the under side of the filter, in order more effectually to separate it, before any chance occurs of its passing into the boiler.
FIG. 1.--Elevation. FIG. 2.--Vertical Section
FIG. 1.--Elevation. FIG. 2.--Vertical Section
The filter consists of wood charcoal in the lower half and bone black above firmly held between two perforated plates, as shown. After the heater has been in use for from three to ten hours, according to the nature of the water used, it is necessary to blow out the heater, in order to clear the filter from deposit. To do this, the cock at R is opened, and the water is discharged by the pressure from the boiler. The steam is allowed to pass through the heater for some little time, in order to clear the filter completely. After this operation, all is ready to commence work again. By this means the filter remains fit for use for months without change of the charcoal.
Where a jet condenser is used, either of two plans may be adopted. One plan takes the feed-water from the hot well and passes the exhaust from the feed pumps through the heater, using at the same time an increased amount of coil for the live steam. By this means a temperature of water is attained high enough to cause deposition, and at the same time to produce decomposition of the oil brought over from the cylinders. The other plan places the heater in the line of exhaust from the engine to the condenser, also using a larger amount of coil. Both these methods work well. The writer sometimes uses the steam from the coil to work the feed pump; or, if the heater stands high enough, it is only necessary to make a connection with the boiler, when the water formed by the condensation of the steam runs back to the boiler, and thus the coil is kept constantly at the necessary temperature.
In adapting the heater to locomotives, we were met with the difficulty of want of space to put a heater sufficiently large to handle the extremely large amount of water evaporated on a locomotive worked up to its full capacity, being from 1,500 to 2,500 gallons per hour, or from five hundred to one thousand h.p. We designed various forms of heaters and tried them, but have finally decided on the one shown in the engraving, Fig. 3, which consists of a lap welded tube, 13 inches internal diameter, 12 feet long, with a cast-iron head which is divided into two compartments or chambers by a diaphragm. Into this head are screwed 60 tubes, one inch outside diameter and 12 feet long, which are of seamless brass. These are the heating tubes, within which are internal tubes for circulation only, which are screwed into the diaphragm and extend to within a very short distance of the end of the heating tube. The exhaust steam for heating is taken equally from both sides of the locomotive by tapping a two-inch nipple with a cup shaped extension on it in such a way as to catch a portion of the exhaust without interfering with the free escape of the steam for the blast, and without any back pressure, as it relieves the back pressure as much as it condenses. The pipe from one side of the engine is connected with the chamber into which the heating tubes are screwed, and is in direct communication with them. The pipe from the other side is connected with the chamber into which the circulating tubes are screwed. The beat of the exhaust, working, as it does, on the quarters, causes a constant sawing or backward and forward circulation of steam without any discharge, and only the condensation is carried off.
The water is brought from the pump and discharged into the lower side of the heater well forward, and passes around the heating tubes to the end, when it is discharged into a pipe that carries it forward, either direct to the check or into the purifier, which is located between the frames under the boiler, and consists of a chamber in which are arranged a live steam coil and a filter above the coil. The water coming in contact with the coil, its temperature is increased from the temperature of the exhaust, 210°, to about 250° Fahr., which causes the separation of the lime salts as before described, and it then passes through the filter and direct to the boiler from above the filter, which is cleansed by blowing back through it as before described.
One of these heaters lately tested showed a saving in coal of 22 per cent, and an increase of evaporation of 1.09 pounds of water per pound of coal.--Franklin Journal.
This precious statue forms the noble figure that adorns the monument erected to the memory of the architect Carles Sada, who died in 1873. This remarkable funereal monument is 20 feet high, the superior portion consisting of a sarcophagus resting upon a level base. Upon this sarcophagus is placed the statue of "La Architectura," which we reproduce, and which well exemplifies the genius of the author and sculptor, Juli Monteverde.--La Ilustració Catalana.
LA ARCHITECTURA.--STATUE BY JULI MONTEVERDE.ERECTED IN MEMORY OF THE ARCHITECT, CARLES SADA.
The illustration shows a gardener's cottage recently erected at Downes, Devonshire, the seat of Colonel Buller, V.C., C.B, C.M.G., from the designs of Mr. Harbottle, A.R.I.B.A., of Exeter. It is built of red brick and tile, the color of which and the outline of the cottage give it a picturesque appearance, seen through the beautiful old trees in one of the finest parks in Devonshire.--The Architect.
Gardener's Cottage at DOWNES for Colonel Buller V.C., C.B., C.M.G.,E.H. HarbottleArchitect
Writing from Gilbertville, a Lewiston journal correspondent says: Gilbertville, a manufacturing community in the town of Canton, twenty-five miles from Lewiston, up the Androscoggin, is now a village of over 500 inhabitants, where three years ago there was but a single farmhouse. If a town had sprung into existence in a far Western State with so much celerity, the phenomenon would not be considered remarkable, perhaps; but growths of this kind are not indigenous to the New England of the present era. Gilbertville has probably outstripped all New England villages in the race of the past three years. It is only one of the signs that old Maine is not dead yet.
Gilbert Brothers erected a saw mill here three years ago. A year later, the Denison Paper Manufacturing Company, of Mechanic Falls, erected a big pulp mill, which, also, the town voted to exempt from taxation for ten years. The mills are valuable companions for each other. The pulp mill utilizes all the waste of the saw mill. A settlement was speedily built by the operatives. Gilbertville now boasts of a post-office, a store, several large boarding houses, a nice school house, and over 500 inhabitants. The pulp mill employs seventy men. It runs night and day. It manufactures monthly 350 cords of poplar and spruce into pulp. It consumes monthly 500 cords of wood for fuel, 45 casks of soda ash, valued at $45 per cask, nine car loads of lime, 24,000 pounds to the car. It produces 1,000,000 pounds of wet fiber, valued at about $17,000, monthly. The pay roll amounts to $3,500 per month.
The larger part of the stock used by the mill consists of poplar logs floated down the Androscoggin and its tributaries. One thousand two hundred cords of poplar cut in four-foot lengths are piled about the mill; and a little further up the river are 5,000 cords more. The logs are hauled from the river and sawed into lengths by a donkey engine, which cuts about sixty cords per day, and pulls out fourteen logs at a time. All the spruce slabs made by the saw mill are used with this poplar. The wood is fed to a wheel armed with many sharp knives. It devours a cord of wood every fifteen minutes. The four-foot sticks are chewed into fine chips as rapidly as they can be thrust into the maw of the chopper. They are carried directly from this machine to the top of the mill by an endless belt with pockets attached. There are hatchways in the attic floor, which open upon rotary iron boilers. Into these boilers the chips are raked, and a solution of lime and soda ash is poured over them.
This bath destroys all the resinous matter in the wood, and after cooking five hours the chips are reduced to a mass of soft black pulp. Each rotary will contain two cords of chips. After the cooking, the pulp is dumped into iron tanks in the basement, where it is thoroughly washed with streams of clean cold water. It is then pumped into a machine which rolls it into broad sheets. These sheets are folded, and condensed by a hydraulic press of 200 tons pressure. This process reduces its bulk fifty per cent., and sends profuse jets of water flying out of it. The soda ash, in which, mixed with lime and water, the chips are cooked, is reclaimed, and used over and over again. The liquor, after it has been used, is pumped into tanks on top of large brick furnaces. As it is heated, it thickens. It is brought nearer and nearer the fire until it crystallizes, and finally burns into an ash. Eighty per cent. of the ash used is thus reclaimed. This process is an immense saving to the pulp manufacturers. The work in the pulp mill is severe, and is slightly tinged with danger.
Three thousand four hundred pounds of white ash to 2,100 pounds of lime are the proportions in which the liquor in each vat is mixed. One does not envy the lot of the stout fellows who crawl into the great rotaries to stow away the chips. The hurry of business is so great that they cannot wait for these boilers to cool naturally, after they have cooked one batch, before putting in another. So they have a fan pump, to which is attached a canvas hose, and with this blow cooling air currents into the boiler, or "rotary," as they call it. The rotary is subjected to an immense pressure, and is very stoutly made of thick iron plates, bolted together.
Describing the business as carried on at Mechanic Falls, the same paper says: There are six of these mills on the three dams over which the Little Androscoggin falls. These are the Eagle, the Star, the Diamond, the Union, the pulp, and the super calendering mills. The Eagle and the Star mills run on book papers of various grades. The Union mill runs on newspaper. The old Diamond mill now prepares pulp stock. The pulp mill does nothing but bleach the rag pulp and prepare for the machines in the other mills; while the super-calendering mill gives the paper an extra finish when ordered. There is practically but one series of processes by which the paper is made in the various mills.
It is a curious fact that America is not ragged enough to produce the requisite amount of stock for its own paper mills. Nearly all the rags used by the Denison Mills (and by others in various parts of the country as well) are imported from the old countries. All the rags first go through the "duster." This is a big cylindrical shell of coarse wire netting. It is rapidly revolved, while a screw running through its center is turned in the opposite direction. Air currents are forced through it by a power fan. The rags are continuously fed into one end of this shell, which is about ten feet long and four feet in diameter. The screw forces them through the whole length of the shell, while they are kept buzzing around and subjected to breezes which blow thick clouds of dirt and dust out of them. The air of the room is thick with European and Asiatic earth. It is swept up in great rolls on the floor. The man who operates the duster should have leather lungs.
Overhead is a long room where thirty girls are busily sorting the rags for the various grades of papers. That the dusting machine is no more perfect than a human machine is evinced by the murky atmosphere of this room, by the particles that lodge in the throat of the visitor, and by the frequent coughing of the sorters. They protect their hair with turbans of veiling, occasionally decorated with a bit of bright color. These turbans give the room the appearance of an industrious Turkish harem. Short, sharp scythe blades, like Turkish scimeters, gleam above all the girls' benches. When a sorter wishes to cut a rag, she pulls it across the edge of this blade, and is not obliged to hunt for a pair of shears.
Curious discoveries are frequently made in the rags. Old pockets, containing small sums of money, are occasionally found. A foreign coin valued at about $3 was found a few days ago. In the paper stock, quaint and valuable old books or pictures are found often. One of the workmen has a museum composed of curiosities found amid the rags and shreds of paper. Rev. Dr. Bolles, of Massachusetts, makes an annual pilgrimage to Mechanic Falls for the sake of the rare old pamphlets, books, and engravings that he may dig out.
Stuffed in hogsheads, the rags are lowered from this room through a hatchway, and are given a red hot lime bath. They are placed in ponderous cylinders of boiler iron, which revolve horizontally in great gears high above the floor. A mixture of lime and water, which has been prepared in large brick vats, is poured over them. An iron door, secured by huge bolts, is closed on them. The cylinder slowly turns around, and churns the rags in the lime-juice twelve hours. This process is called bleaching. When the rags come out they are far from white, however. They are of a uniform dirty brown hue. But the colors have lost their gripe. When the rags shall have been submitted to the grinding and washing in pure water, as we shall see them presently, they are easily whitened. The lime bath is the purgatory of the paper stock.
Before we go any further, we must see what becomes of those soft and lop-sided bundles which are going into the mills. These contain chemically prepared wood fiber, a certain percentage of which is used in nearly all the papers made now. It gives the paper a greater body, although its fiber is not so strong as that made of rags. The pulp comes down from Canton in soft brown sheets. These are at once bleached. The brown fiber is placed in a bath of cold water and chlorate of lime. There it quietly rests till a sediment settles at the bottom of the tank. At an opportune moment the workman pours in a copious libation of boiling water. This causes the escape of the chlorine gas, which destroys all the color in the pulp. In half an hour it comes out, a mass of smoking fibers as white as a snow heap. The drainers into which it goes are large pens with perforated tile floors. The pulp remains in the drainers till it so dry it is handled with a pitchfork.
We are now ready to look at the beating machines, which have to perform a very important part in paper making. These are large iron tanks with powerful grinders revolving in them. Barrow loads of the brown rags are dumped into them, and clear cold water is poured in. The grinders are then started. They chew the rags into fine bits. They keep the mass of rags and water circulating incessantly in the tanks. Clean water constantly flows in and dirty water as constantly flows out. In the course of six hours the rags are reduced to a perfectly white pulpy mass. There is one mill, as we have said, devoted exclusively to the reduction of rags to this white pulp. It is dried in drainers such as we saw a few moments ago filled with the wood fiber.
There are other beating machines just like these, which perform a slightly different service. Their function may be compared to that of an apothecary's mortar or a cook's mixing dish. The white rag stock and the white wood fiber are mixed in these, in the required proportions. At this stage, the pulp is adulterated with China clay, to give it substance and weight; here the sizing (composed of resin and sal soda) is put in; oil of vitriol, bluing, yellow ocher, and other chemicals are added, to whiten or to tint the paper. These beaters are much like so many soup kettles. Upon the kind, number, and proportion of the ingredients depends the nature of the product. The percentages of rag pulp, wood pulp, clay, coloring, etc., used, depend upon the quality of paper ordered.
After the final beating, the mixture descends into a large reservoir called the "stuff chest," whence it is pumped to the paper machine. The pulp is of the consistency of milk when it pours from the spout of the pumps on the paper machine. The latter is a complicated series of rollers, belts, sieves, blankets, pumps, and gears, one hundred feet long. To describe it or to understand a description of it would require the vocabulary and the knowledge of a scientist. The milky pulp first passes over a belt of fine wire cloth, through which the water partly drains. It is ingeniously made to glide over two perforated iron plates, under which pumps are constantly sucking. You can plainly see the broad sheet of pulp lose its water and gain thickness as it goes over these plates. Broad, blanket-like belts of felt take it and carry it over and between large rolling cylinders filled with hot steam. These dry and harden it into a sheet which will support itself; and without the aid of blankets it winds among iron rolls, called calenders, which squeeze it and give it surface. It is wound upon revolving reels at the end of the machine.
If a better surface or gloss is required, it is carried to the super calendering mill, where it is steamed and subjected to a long and circuitous journey up and down tall stands of calenders upon calenders. The paper is cut by machines having long, winding knives which revolve slowly and cut, on the scissors principle--no two points of the blade bearing on the paper with equal pressure at once. Girls pack the sheets on the tables as they fall from the cutters, and throw out the damaged or dirtied sheets. A small black spot or hole or imperfection of any sort is sufficient to reject a sheet. In some orders fifty per cent. of the sheets are thrown out. There is no waste, as the damaged paper is ground into pulp again. Having been cut, the paper must be counted and folded. Then it is packed into bundles for shipment. The young lady who does the counting and folding is the wonder of the mill. Giving the sheets a twist with one hand so as to spread open the edges, she gallops the fingers of the other hand among them; and as quickly as you or I could count three, she counts twenty-four and folds the quire. She takes four sheets with a finger and goes her whole hand and one finger more; thus she gets twenty-four sheets. Long practice is required to do the counting rapidly and accurately. Twenty-four sheets, no more and no less, are always found in her quires.
Papers of different grades are made of different stock, but by the same process. Some paper stock is used. This must be bleached in lime and soda ash. There are powerful steam engines in the mills for use when the water is low. There are large furnaces and boilers which supply the steam used in the processes.
The Messrs. Denison employ 175 hands at Mechanic Falls. Their pay roll amounts to about $5,000 per month. The mills produce 350,000 pounds of paper per month and they ship several car-loads of prepared wood-pulp, in excess of that required for their own use, weekly. The annual value of their product is not far from $300,000. They use, for sundries, each month, 300 tons of coal, 100 casks of common lime, 250 gallons of burning-oil, 28,000 pounds of chlorate of lime, 3,700 pounds of soda ash. 10,000 pounds of resin. 24,000 pounds of sal soda, 22,000 pounds of oil of vitriol, 22,000 pounds of China clay, etc.
By M. YATES, Hon. Sec. Bread Reform League, London.
It is well recognized that defective mineral nutrition is an important factor in the production of rickets and bad teeth, but as its influence in predisposing toward tuberculous disease is not so clearly ascertained, will you kindly allow public attention to be directed to a statement which was discussed at the Social Science and Sanitary Congresses and which, if confirmed by further scientific research, indicates a simple means of diminishing consumption, which, as Dr. William Fair, F.R.S., says, "is the greatest, the most constant, and the most dreadful of all the diseases that affect mankind." In "Phosphates in Nutrition," by Mr. M.F. Anderson, it is stated that although the external appearances and general condition of a body when death has occurred from starvation are very similar to those presented in tuberculous disease, in starvation, "from wasting of the tissues, caused by the combustion of their organic matter, there would be an apparentincreasein the percentage proportion of mineral matter; on the other hand, in tubercular disease, there would be a materialdecreasein the mineral matter as compared with the general wasting." Analyses, made by Mr. Anderson, of the vascular tissues of patients who have died of consumption, scrofula, and allied diseases, show "a very marked deficiency in the quantity of inorganic matter entering into their composition; this deficiency is not confined to the organs or tissues which are apparently the seat of the disease, but in a greater or lesser degree pervades the whole capillary system."
The observations of Dr. Marcet, F.R.S., show that in phthisis there is a considerable reduction of the normal amount of phosphoric acid in the pulmonary tissues; and it is very probable that there is a general drain of phosphoric acid from the system.
This loss may be caused by the expectoration and night-sweats, or it may also be produced by defective mineral nutrition, either from deficient supply in the food, or from non assimilation. But, whatever causes this deficiency, it is universally acknowledged that it is essential the food should contain a proper supply of the mineral elements. If the body is well nourished, the resisting force of the system is raised. Professor Koch and others, who accept the germ theory of disease to its fullest extent, state that the minute organisms of tubercular disease do not occur in the tissues of healthy bodies, and that when introduced into a living body their propagation and increase are greatly favored by a low state of the general health.
Dr. Pavy, F.R.S., showed in his address on the "Dietetics of Bread" that in white flour, instead of obtaining the 23 parts of mineral matter to 100 parts of nitrogenous matter--which is the accepted ratio of a standard diet--we should only get 4.20 parts of mineral matter. Professor Church states that 1 lb. of white flour has only 49 grains of mineral matter, while 1 lb. of whole wheat meal has 119 grains. Whole wheat meal, besides containing other essential mineral elements, has double the amount of lime, and nearly three times the amount of phosphoric acid; so that if defective mineral nutrition in any way predisposes to consumption, the adoption of wheat meal prepared in a digestible and palatable form is of primary importance for those who are unable to obtain the phosphates from high-priced animal foods.
Wheat meal has also great advantages for those who are able to afford animal food, for, as Dr. Pavy stated, "It acts as a greater stimulant to the digestive organs."
It is probably due to this stimulating property of wheat meal that people who have adopted it find they can digest animal fat much better than previously. If this is corroborated by general experience, it may be of great benefit in aiding the system to resist tendencies toward consumption and scrofula, for these diseases are generally accompanied by loss of the power of assimilating fat. It is believed that a deficiency of oleaginous matter is a predisposing cause of tuberculous disease. An important prophylactic, therefore, against such maladies, would be a general increase in the use of butter and other fatty foods.
There is such good reason to believe that a low state of nutrition favors the development of tuberculous disease, that parents cannot be too strongly urged to provide their children with a proper supply of healthy, nourishing, and pure food (under which term must, of course, be included pure air and pure water), for by so doing they may often arrest consumptive tendencies, and thus would be diminished the ravages of that fatal disease which, when once established, is "the despair of the physician, and the terror of the public."
The capacity of the New York State fish farm at Caledonia is 6,000,000 fry a year. The recently issued report of the fish commissioners says that this year the ponds will be worked to their full capacity.
The supply of spawn has been greater than could be hatched there, and supplies were sent to responsible persons in every State in the Union to be experimented with. At the date of issuing the report the supply of stock fish at the hatchery embraced, it was estimated, a thousand salmon trout, of weights ranging from four to twelve pounds; ten thousand brook trout, from half a pound to two pounds in weight; thirty thousand California mountain trout, weighing from a quarter of a pound to three pounds; forty-seven hundred rainbow trout, of from a quarter of a pound to two pounds' weight; and a large number of hybrids produced by crossing and interbreeding of different members of the salmon tribe. In this connection reference is made to the interesting fact that hybrids of the fish family are not barren. Spawners produced by crossing the male brook trout with the female salmon trout cast 72,000 eggs last fall, which hatched as readily as the spawn of their progenitors. The value of the stock of breeding fish at the hatchery is estimated at $20,000.
The hatch of salmon trout this season was not far from 1,200,000, and these will be distributed chiefly in the large lakes of the interior. About a million little brook trout were produced. The commission doubts whether much benefit has resulted from attempting to stock small streams that have once been good trout waters, but the temperature of which has been changed by cutting away the forest trees that overhung them. The best results have been attained where the waters are of considerable extent, especially those in and bordering on the wilderness in the northern part of the State. The experiments with California trout, have been very successful, and it is found that the streams most suitable for them, are the Hudson, Genesee, Mohawk, Moose, Black, and Beaver rivers, and the East and West Canada creeks. The commission hopes to hatch 6,000,000 or 8,000,000 shad this season at a cost of about $1,000. Concerning German carp, the commissioners find that the water at Caledonia is too cold for this fish, but think that carp would do well in waters further south.
The commission awaits a more liberal appropriation of money before beginning the work of hatching at the new State fish farm at Cold Spring, on the north side of Long Island, thirty miles out from Brooklyn.
Grant Allen, an English evolutionist, gives this imaginary picture of our supposed ancestor: "We may not unjustifiably picture him to ourselves as a tall and hairy creature, more or less erect, but with a slouching gait, black faced and whiskered, with prominent, prognathous muzza, and large, pointed canine teeth, those of each jaw fitted into an interspace in the opposite row. These teeth, as Mr. Darwin suggests, were used in the combats of the males. His forehead was no doubt low and retreating, with bony bosses underlying the shaggy eyebrows, which gave him a fierce expression, something like that of the gorilla. But already, in all likelihood, he had learned to walk habitually erect, and had begun to develop a human pelvis, as well as to carry his head more straight on his shoulders. That some such animal must have existed seems to me an inevitable corollary from the general principles of evolution and a natural inference from the analogy of other living genera."
As well known, the method by which glass barometer tubes are made gives them variable calibers. Not only do the different tubes vary in size, but even the same tube is apt to have different diameters throughout its length, and its sections are not always circular. Manufacturers of barometers often have need to know exactly the dimensions of the sections of these tubes, and to ascertain whether they are equal throughout a certain length of tube, and this is especially necessary in those instruments in which the surfaces of the sections of the reservoir and tube must bear a definite ratio to one another. Having ascertained that no apparatus existed for measuring the caliber of these and anolagous tubes, and that manufacturers had been accustomed to make the measurements by roundabout methods, Colonel Goulier has been led to devise a small apparatus for the purpose, and which is shown in the accompanying cuts.
GOULIER'S TUBE GAUGE. (Plan and longitudinal and tranverse sections.)
GOULIER'S TUBE GAUGE. (Plan and longitudinal and tranverse sections.)
The extremity of a brass tube, T, 0.5 to 0.6 of a meter in length and smaller in diameter than the tube to be gauged, is cut into four narrow strips a few centimeters in length. The extremity of each of these strips is bent toward the axis of the tube. Two of them, m and m', opposite each other are made very flexible, and carry, riveted to their extremities, two steel buttons, the heads of which, placed in the interior, have the form of an obtuse quoin with rounded edge directed perpendicular to the tube's axis. The other extremities of these buttons are spherical and polished and serve as caliper points in the operation of measuring. These buttons are given a thickness such that when the edges of their heads are in contact, the external diameter of the tube exceeds the distance apart of the two calibrating points by more than one millimeter. But such distance apart is increased within certain limits by inserting between the buttons a German silver wedge, L, carried by a rod, t, which traverses the entire tube, and which is maneuvered by a head, B, fixed to its extremity. This rod carries a small screw, v, whose head slides in a groove, r, in the tube, so as to limit the travel of the wedge and prevent its rotation. Beneath the head, B, the rod is filed so as to give it a plane surface for the reception of a divided scale. A corresponding slit in the top of the tube carries the index, I, of the scale. The principal divisions of the scale have been obtained experimentally, and traced opposite the index when the calibrating points were exactly 7, 8, 9 etc., millimeters apart. As the angle of the wedge is about one tenth, the intervals between these divisions are about one centimeter. These intervals are divided into ten parts, each of which corresponds to a variation in distance of one tenth of a millimeter.
To calibrate a glass tube with this instrument, the tube is laid upon the table, the gauge is inserted, and the buttons are introduced into the section desired. The flat side of the head, B, being laid on the table, arranges, as shown in the figure, the buttons perpendicular to it. Then the measuring wedge is introduced until a stoppage occurs through the contact of the buttons with the sides of the tube. Finally, their distance apart is read on the scale. Such distance apart will be the measure of a diameter or a chord of the tube's section, according as the buttons have been kept in the diametral plane or moved out of it. In order that the operator shall not be obliged to watch the position of the line of calibrating buttons in obtaining the diameter, the following arrangement has been devised: The sides of the measuring wedge are filed off to a certain angle, and the ends of the corresponding strips, d and d', are bent inward in the form of hooks, whose extremities always rest on the faces of the directing wedges. The length of these hooks and the angle of the wedge are such that the distance apart of the rounded backs of the directing strips is everywhere less, by about one-thirtieth, than that of the calibrating buttons. From this it will be seen that if the wedge be drawn back, and inserted again after the tube has been turned, we shall measure the diameter that is actually vertical. It becomes possible, then, to determine the greatest and smallest diameters in a few minutes; and, supposing the section elliptical, its area will be obtained by multiplying the product of these two diameters by pi/4.
From the description here given it will be seen that Colonel Goulier's apparatus is not only convenient to use, but also permits of obtaining as accurate results as are necessary. Two sizes of the instrument are made, one for diameters of from 7 to 10.5 mm., and the other for those of from 10 to 15.5 mm. It is the former of these that is shown, of actual size, in the cuts.
The following method for soldering without the use of a soldering iron is given in theTechniker:
The parts to be joined are made to fit accurately, either by filing or on a lathe. The surfaces are moistened with the soldering fluid, a smooth piece of tin foil laid on, and the pieces pressed together and tightly wired. The article is then heated over the fire or by means of a lamp until the tin foil melts. In this way two pieces of brass can be soldered together so nicely that the joint can scarcely be found.
With good soft solder, nearly all kinds of soldering can be done over a lamp without the use of a "copper." If several piaces have to be soldered on the same piece, it is well to use solder of unlike fusibility. If the first piece is soldered with fine solder composed of 2 parts of lead, 1 of tin, and 2 of bismuth, there is no danger of its melting when another place near it is soldered with bismuth solder, made of 4 parts of lead, 4 of tin, and 1 of bismuth, for their melting points differ so much that the former will not melt when the latter does. Many solders do not form any malleable compounds.
In soldering together brass, copper, or iron, hard solder must be employed; for example, a solder made of equal parts of brass and silver (!). For iron, copper, or brass of high melting point, a good solder is obtained by rolling a silver coin out thin, for it furnishes a tenacious compound, and one that is not too expensive, since silver stretches out well. Borax is the best flux for hard soldering. It dissolves the oxides which form on the surface of the metal, and protects it from further oxidation, so that the solder comes into actual contact with the surfaces of the metal. For soft soldering, the well-known fluid, made by saturating equal parts of water and hydrochloric acid with zinc, is to be used. In using common solder rosin is the cheapest and best flux. It also has this advantage, that it does not rust the article that it is used on.--Deutsche Industrie Zeitung.
From a letter in the Grass ValleyTidingswe make the following extracts:
The Spenceville Copper Mining Company have 43 acres of copper-bearing ground and 100 acres of adjoining land, which was bought for the timber. There are a hoisting works, mill, roasting sheds, and leaching vats on the ground, and they cover several acres.
On going around with Mr. Ellis, the first place we came to was the mine proper, which is simply an immense opening in the ground covering about one half of an acre, and about 80 feet deep. It has an incline running down into it, by which the ore is hoisted to the surface. Standing on the brink of this opening and looking down, we could see the men at work, some drilling, others filling and running the cars to the incline to be hoisted to the surface.
The ore is found in a sort of chloritic slate and iron pyrites which follow the ledge all around. The ore itself is a fine-grained pyrite, with a grayish color, and it is well suited by its sulphur and low copper contents, as well as by its properties for heap roasting. In heap roasting, the ore is hand-broken by Chinamen into small lumps before being hoisted to the surface. From the landing on the surface it is run out on long tracks under sheds, dumped around a loose brick flue and on a few sticks of wood formed in the shape of a V, which runs to the flues to give a draught. Layers of brush are put on at intervals through the pile. The smaller lumps are placed in the core of the heap, the larger lumps thrown upon them, and 40 tons of tank residues thrown over all to exclude excess of air; 500 lb. of salt is then distributed through the pile, and it is then set afire. After well alight the draught-holes are closed up, and the pile is left to burn, which it does for six months. At the expiration of that time the pile is broken into and sorted, the imperfectly roasted ore is returned to a fresh roast-heap, and the rest trammed to the
These are 50 in number, 10 having been recently added. The first 40 are four feet by six feet and four feet deep, the remaining 10 twice as large. About two tons of burnt ore is put in the small vats (twice as much in the larger ones), half the vats being tilled at one time, and then enough cold water is turned in to cover the ore. Steam is then injected beneath the ore, thus boiling the water. After boiling for some time, the steam is turned off and the water allowed to go cold. The water, which after the boiling process turns to a dark red color, is then drawn off. This water carries the copper in a state of solution. The ore is then boiled a second time, after which the tank residues are thrown out and water kept sprinkling over them. This water collects the copper still left in the residues, and is then run into a reservoir, and from the reservoirs still further on into settling tanks, previous to
and is then conducted through a system of boxes filled with scrap iron, thus precipitating the copper.
The richer copper liquors which have been drawn from the tanks fire not allowed to run in with that which comes from the dump heaps. This liquor is also run into settling tanks, and from them pumped into four large barrels, mounted horizontally on friction rollers, to which a very slow motion is given. These barrels are 18 feet long and six feet six inches deep outside measure. They are built very strongly, and are water-tight. Ten tons of scrap iron are always kept in each of these barrels, which are refilled six times daily, complete precipitation being effected in less than four hours. Each barrel is provided with two safety valves, inserted in the heads, which open automatically to allow the escape of gas and steam. The precipitation of the copper in the barrels forms copper cement. This cement is discharged from the barrels on to screens which hold any lumps of scrap iron which may be discharged with the cement. It is then dried by steam, after which it is conveyed into another tank, left to cool, and then placed in bags ready for shipment, as copper cement. The building in which the liquor is treated is the mill part of the property, from which they send out 42 tons monthly of an average of 85 per cent, of copper cement, this being the average yield of the mine.
There are 23 white men and 40 Chinamen employed at the mine and the mill. There are also several wood choppers, etc., on the company's pay-roll. Eight months' supply of ore is always kept on hand, there now being 12,000 tons roasting. The mine is now paying regular monthly dividends, and everything argues well for the continuance of the same.
The Thomson pile, which is employed with success for putting in action the siphon recorder, and which is utilized in a certain number of cases in which an energetic and constant current is needed, is made in two forms. We shall describe first the one used for demonstration. Each element of this (Fig. 1) consists of a disk of copper placed at the bottom of a cylindrical glass vessel, and of a piece of zinc in the form of a grating placed at the upper part, near the surface of the solution. A glass tube is placed vertically in the solution, its lower extremity resting on the copper. Into this tube are thrown some crystals of sulphate of copper, which dissolve in the liquid, and form a solution of a greater density than that of the zinc alone, and which, consequently, cannot reach the zinc by diffusion. In order to retard the phenomenon of diffusion, a glass siphon containing a cotton wick is placed with one of its extremities midway between the copper and zinc, and the other in a vessel outside the element, so that the liquid is sucked up slowly nearly to its center. The liquid is replaced by adding from the top either water or a weak solution of sulphate of zinc.
FIG. 1.--THE THOMSON PILE.(Type for demonstration.)
FIG. 1.--THE THOMSON PILE.(Type for demonstration.)
The greater part of the sulphate of copper that rises through the liquid by diffusion is carried off by the siphon before reaching the zinc, the latter being thus surrounded with an almost pure solution of sulphate of copper having a slow motion from top to bottom. This renewal of the liquid is so much the more necessary in that the saturated solution of sulphate of copper has a density of 1.166, and the sulphate of zinc one of 1.445, There would occur, then, a mixture through inversion of densities if the solution were allowed to reach a too great amount of saturation, did not the siphon prevent such a phenomenon by sucking up the liquid into the part where the mixture tends to take place. The chemical action that produces the current is identical with that of the Daniell element.
In its application, this pile is considerably modified in form and arrangement. Each element (Fig 2) consists of a flat wooden hopper-shaped trough, about fifty centimeters square, lined with sheet lead to make it impervious. The bottom is covered with a sheet of copper and above this there is a zinc grate formed of closely set bars that allow the liquid to circulate. This grate is provided with a rim which serves to support a second similar element, and the latter a third, and soon until there are ten of the elements superposed to form series mounted for tension. The weight of the elements is sufficient to secure a proper contact between the zinc and copper of the elements placed beneath them, such contact being established by means of a band of copper cut out of the sheet itself, and bent over the trough.
FIG. 2.--THE THOMSON PILE. (Siphon Recorder Type.)
FIG. 2.--THE THOMSON PILE. (Siphon Recorder Type.)
On account of the large dimensions of the elements, and the proximity of the two metals, a pile is obtained whose internal resistance is very feeble, it being always less than a tenth of an ohm when the pile is in a good state, and the electromotive force being that of the Daniell element--about 1 08 volts.
Sometimes the zinc is covered with a sheet of parchment which more thoroughly prevents a mixture of the liquids and a deposit of copper on the zinc. But such a precaution is not indispensable, if care be taken to keep up the pile by taking out some of the solution of sulphate of zinc every day, and adding sulphate of copper in crystals. If the pile is to remain idle for some time, it is better to put it on a short circuit in order to use up all the sulphate of copper, the disappearance of which will be ascertained by the loss of blue color in the liquid. In current service, on the contrary, a disappearance of the blue color will indicate an insufficiency of the sulphate, and will be followed by a considerable reduction in the effects produced by the pile.
The great power of this pile, and its constancy, when it is properly kept up, constitute features that are indispensable for the proper working of the siphon recorder--the application for which it was more especially designed.
This apparatus has been also employed under some circumstances for producing an electric light and charging accumulators; but such applications are without economic interest, seeing the enormous consumption of sulphate of copper during the operation of the pile. The use of the apparatus is only truly effective in cases where it is necessary to have, before everything else, an energetic and exceedingly constant current.--La Nature.