CHAPTER IV.VULCANIZATION.
The importance of the improvements in gum-elastic for educational purposes, has been previously commented upon in previous portions of these notices, and we would now give a little additional space to some of the many purposes in this direction, which assist in filling up the almost infinite measure of the uses of vulcanized India-rubber. Much has been done to perfect them, but enough has already been accomplished to prove that the causes of education will hereafter be promoted by the use of many articles made of the vulcanized fabrics. The cheapness of some of these articles, compared with the cost of those of other materials, gives double assurance of the correctness of this view. The expensiveness of globes, for instance, which are admitted by all to be by far the best means of imparting and obtaining geographical and astronomical information, has rendered them accessible to few persons, either pupils or teachers. The adaptation and application of gum-elastic to these purposes, will bring within the reach of every youth in the commonest school, a perfect globe, at a price within their means, and maps more durablethan leather or parchment, at cheaper rates than paper maps are now made when mounted on linen.
The outline maps which we have seen, are printed upon the vulcanized India-rubber fabrics, both transparent and opaque, and also upon various articles to be used for other purposes besides maps, such as piano covers, crumb cloths, and carpets. Arrangements are being made for this manufacture, which may facilitate the method of teaching from outline maps by printing on this material, maps of the world, upon a scale large enough for “papering” the sides of an ordinary sized room of a school house, academy, public lecture room, or dwelling. The same map, when suspended at a suitable distance from the wall, with lights placed behind it, may be used as a transparency for teaching at night. A series of sectional maps printed on a scale as large as can be conveniently printed upon calenders, after the manner of calico-printing, may be cemented together, and arranged upon rollers.
The globe has heretofore been so expensive, as to be found only in schools of the higher class. No form of map or atlas can give so correct an idea of the surface of the earth, or of the relative situation of places, as a globe. An attempt appears to have been made by Mr. Goodyear to make them of gum-elastic, soon after the discovery of the “acid gas process.” These attempts have been followed up at intervals, until the production of the present process.They are made of various sizes, and when embossed by the method described in the manufacture of hollow ware—by steam and vulcanization—they may be made to supply the present deficiency of globes for the blind.
Their utility and importance to the cause of education need not, we are sure, be insisted upon, when it is understood that any child can be furnished with a perfect globe at a price to come within ordinary means. When used they are inflated with air, and when collapsed, may be folded in so small a compass as to be no incumbrance under any circumstances. When the large sizes are filled with hydrogen they become highly ornamental and beautiful objects.
CHAPTER V.ADULTERATION OF INDIA-RUBBER—(Caoutchouc.)
Every article of commerce that is susceptible of adulteration is sure to fall into the hands of those who seem to be peculiarly educated to the work of diluting, and reducing by various chemical processes the real value of the article to be counterfeited. No matter how cheap the pure substance can be obtained, some method must be conjured up by which the innocent purchaser or consumer is unconsciously duped. India-rubber and gutta-percha are among the vegetable gums, which have beenmost extensivelyadulterated. It long since became a matter of scientific research in England, to ascertain how great a per cent. India-rubber could be reduced, by the admixture of worthless compounds, and the same skill has been thus perverted in our own country.
In Prussia, a law was passed in 1856, making the adulteration of chemicals and articles of consumption by which life shall be endangered, an offence punishable with death. The simple adulteration of food or drink with any deleterious substance, is punishablewith fifteen years’ hard labor; and any other adulteration is regarded as cheating (betrug), and is punished accordingly. However severe or stringent these laws may seem to a republican mind, they are nevertheless just. What is the sale of an adulterated article, but the obtaining of money under false pretences, and why should not every rude infraction of the law of right, be visited by some adequate penalty?
A series of letters were published in 1856, in England, under the above caption, which shows very clearly the extent to which the practice of adulteration had then been carried. We herewith give the most important statement contained in those letters. The letters referred to were written by William H. Herbert, Esq., and addressed to the Editor of the London Mechanics’ Magazine.
He commenced the series by remarking that as adulteration by cheap compounds mixed with caoutchouc or India-rubber, are extensively used by engineers, he desires to submit a brief account of the processes, etc., by which they are mixed. Java and Para rubber will float upon water, and all manufactured goodsfree of foreign matter, are of the same density; and just in proportion as manufactured articles, such as valves, rail buffers, carriage and engine springs, washers, hose, &c.,sink in water, so in exact ratio, are they adulterated with some cheap pigment, of which the following are a few, and usually in extent from 30 to 100 per cent. Say then, chalk, Paris white, Cornwall or porcelain clay, barytes, oxide zinc, white and red lead, ivory black, lampblack,black lead, Spanish brown, &c., &c. Interested manufacturers will tell you they improve the article, bear greater pressure, &c.; but as a rule this is amere trade subterfuge, the truth being, it enables manufacturers to obtain extortionate profits, which, when I submit theexact formulas, will bevery clearly seen.
Engineers do not seem sufficiently alive to this question of density. Of course in colored articles, it is necessary to usesomepigment, but it is themonstrous excessthat I wish to expose, and applies more particularly to the American inodorous system. I think it only fair to Messrs. Mackintosh & Co., to admit, that most of their goods I have examined float on water; but I know nothing, and have no interest whatever in their establishment, but simply state the fact, because I have found they form the exception to this adulterating or mixing system.
What I wish more especially to impress upon the minds of engineers, is the ready mode they have of discovering or ascertaining whose make is best and cheapest, and it is more likely an India-rubber valve of same dimensions at 2s.6d.per lb., willcost more moneythan one at 4s.6d.per lb., arising solely from the extravagant mixture of these cheap pigments, and its great density over the latter. Java India-rubber, which is mostly used, is at this moment about 7d.per lb., and best Para sheet about 1s.11d.* * If they are fair goods for usual work, then I trust the information I supply may enable contractors to obtain their wants by competition, furnishing their own form. This will realize a great saving to them;but they must not be induced to accept goods of greater density under the plea of being better. The Java gum used in these adulterated articles is ground without undergoing the process of cleansing, but in all articles of light density, the cleaning machine frees it from all gritty matter, and it is usually employed in this cleansed state for such, as well as all gray or white goods.
Messrs. Mackintosh & Co., claim in their patent for vulcanizing all the preparations of sulphur, and without it, so far as I know and believe, no substitute has yet, or is likely to be discovered at a price which can render it commercially available. Indeed, I doubt whether any other than sulphurous bodies will vulcanize, or render fit for the use of the engineers the gum called India-rubber. Hence, the reason why many of the manufacturers are licensed under that firm, and subject to have their goods so stamped. The American inodorous makers attempted to shield themselves, (but on legally trying the point) in vain. The screen against Mr. Mackintosh’s patent was called, as a blind, “hypo.” It is prepared in several ways, but is a compound of sulphur and lead, and when perfect and the lime well washed away, is a very excellent black, costing about 30s.per cwt.; but its whole efficacy rests with the sulphur, and without it would not vulcanize, (though lead works kindly with caoutchouc). This chemical contains about 20 per cent., of sulphur, consequently, five pounds is about equal to twenty-five ounces of sulphur. This extra cost was readily submitted to, rather than to knuckle under to Messrs. Mackintosh’spatent. In many cases it was only said to be used, and what really was used, was white lead or lampblack, oxide of zinc, all in connection with sulphur, according as the color of the goods required, rendered necessary. It was pretended also, by these inodorous manufacturers, that white goods, such as the elastic beds, advertised as “Improved Hydrostatic Beds,” and “Hospital Sheeting,” were vulcanized with sulphuret of zinc, prepared chemically; when, in fact, it is well known that the cost of manufacture is quite prohibitory, and is only of value in proportion to its richness in sulphur. What was in reality used, was, and is, the “yellow sulphur,” and the “pure precipitate of that article.” I mention these things to clear the mystification it may be to the interest of manufacturers to keep up, and as I only write from experience, I have reason to believe your readers, who are interested, will better understand the nature and value of unmixed and mixed caoutchouc, after my fund on this topic is exhausted. With these remarks I will give the recipe for common black packing at 2s.2d.per lb., in quantity, discount as agreed.
The chemical termed “hypo” is manufactured thus: The sugar of lead is made into a solution with water in a separate vessel. The sulphur and lime are then boiled in water, so as to make a solution of sulphur with the lime. The latter solution (clear) is then poured into the former, which unites with the sulphur, and the precipitate is the “hypo.” The hypo is then washed and dried. The lime merely enables the lead to take up the sulphur.
The above is 110 or 112 per cent. of adulteration.
I should here remark, there is also a kind of packing in use, which perhaps is practically best known as “Rag Packing,” made principally from the useless cuttings in the manufacture of India-rubber coats, where the gum is run or spread on calico foundations, which is usually the case with water-proof garments offered for sale at the shops. It is made as follows:
Rag packing for valves, bearing springs, or in sheets of any thickness, where less elasticity is required, and great pressure.
This is sold at 2s.per lb. in very large quantities, or 1s.6d., if a shrewd man, net, or a small discount for cash.
Our gardens, fire engines, brewers, and pump-makers (for suction, &c.,) have found the value of this gum, and the following is the form used with success, and perhaps the adulterations are the best substitutes for pure caoutchouc that the cheap compound market offers.
This is spread upon flax cloth, (Messrs. Richards & Co., Broad Street, are manufacturers,) which weighs 10, 16, and 32 ounces to the square yard, and is about the same cost as the compound, so that theweightis thetruest criterion of cost, and is so calculated by the manufactory. * * * *
Excepting garments every other description of black goods are made from such forms as I have figured, with very little variation according to the requirements of the engineer, and which needs very little judgment or experience to meet. To those who cling to these heavy goods, the formulas I have rendered will enable them to have supplies at a fair competing charge according to quality, and it is theirown fault entirelyif they persist inpurchasing 100 per cent. of cheap powderat thesamecharge as for “pure caoutchouc” of a third of their density.
Your readers must be good enough not to lose the fact of “specific gravity,” and test all the above goods made with pure, unadulterated India-rubber, by their floating on water. Any deviation from this is a proof of some cheap stuff unfairly introduced. It will be just in proportion as they keep themselves well posted up in this matter, that manufacturers will be sly of throwing into their caoutchouc such mad and infamous proportions of cheap adulterations, and drive them (for they will not volunteer) to the necessity of manufacturing from the pure gum, and thus place better disposed traders upon a more just footing, and enable the latter to compete (if need be) upon their own terms, or upon recipes supplied by the engineer. Another fact must not be lost sight of, and that is the use of “light carbonate of magnesia,” which, mixed with the gum, does not increase its density, as will in some measure be illustrated by the recipe I shall now figure out, merely remarking that a somewhat heavy carbonate was used, as well as in an unroasted, and hence the somewhat increased density. This article is worth the attention of buyers of rubber goods, as in a moderate quantity it reduces the costs without correspondingly injuring the manufacturer. (Light buffer spring just sinks in water.)
This is brown at first, but in a few days the sulphur blows over the surface grey or white, andwould lead an amateur to judge they were of that color throughout. Buffer springs and other moulded goods from this compound are a little heavier than Messrs. Mackintosh and Co.’s. A density railway spring, at 4s.per lb. gross, and were made at first to meet it, also sold at 2s.6d.per lb. net. It is a most useful spring, and in competition should be bought at 1s.3d.to 1s.6d.per lb. net, but I should strongly recommend that engineers try a substitute of all “Java gum,” by obtaining a fewaway from their usual manufacturer,ON TRIAL, as I believe their quality as a spring would not be injured, and the price would be reduced, and, moreover, it would guard against the manufacturer being left tempted to do so, without reducing the charge.
For the guidance of engineers, I remark, that a spring of this quality and dimensions, 4½ × 2½ × 1, pressed to half an inch, showed 3½ tons on the dial, and one with equal quantities of oxide of zinc and magnesia, of same size, &c., indicated 1½ tons on equal pressure, while the quality of Mackintosh and Co.’s, referred to before, and of which this was an intimation, marked 1¾ tons on the dial; of course, a spring with a smaller bore than 2½ inches would show greater tonnage.
The next recipe is for grey packing, which is largely and exclusively used by some dealers for marine engines, &c., as well as in sheet; and if the price (3s.6d.per lb.) was notexcessivefor so much adulterated matter, I would pass it over in silence as a very fair and useful article, and if approved, my form will enable the engineer to obtain it much cheaper by competition.
Say then,
So that it costs 25 cts. per lb., and hence I submit that 75 cts. per lb. isexcessive, with discount from 10 to 20 per cent. Unless the magnesia in this packing is well calcined it will cut porous, but does not show its valves cut to shape before vulcanizing. It may seem I lay too much stress upon high prices, and if the goods were bought in trifling quantities, it would carry argument; but as the orders are usually large, and show good monied invoices, there is a wide margin for reduction; besides in many cases these long prices prohibit the use of caoutchouc.The prices are about right if the goods were of pure India-rubber.
I ought to remark that in all formulas which I use,Para rubber is used, which is now nearlyfour times the cost of Java, and is frequently more. This circumstance has for some time been attracting the attention of manufacturers, and bids fair to shut out almost the use of the former in all goods confined in moulds to vulcanize. I would call the especial attention of engineers to this fact, as Java materially reduces the cost, and needs very little judgment on their part to adopt it in these forms, in place of the expensive kind. I do not say it is so strong a gumas Para, but I feel certain that the manufacturers will be awake, and use it, without perhaps yielding the advantage out of their own factories, and therefore it is necessary for consumers to try how far they can “assist themselves” without their benevolence, especially as “Java gum” is now so readily and cheaply cleansed of all dirt or gritty matter. These remarks apply to the recipe I now hand, which is termed—best pure spring, or washers, &c.
This costs about 33 cts. per lb. and is sold at $1 per lb., and though heavier, is intended to meet Messrs. Mackintosh and Co’s. article at $1 12½. The difference in density renders the latter the cheapest to the consumer, while the reduced price of the former catches the unsuspecting trader in these goods, and frequently obtains his preference.
The companion quality to the above for large valves, and packing sheets, is made as follows, and is styled—best pure packing.
This costs about 31 cts. per lb. and is sold at $1 per lb., and is a trifle heavier than the pure spring quality.
It will be perceived that sometimes pure sulphur is used, and sometimes the common flour of sulphur; the former is thought to render the goods more soft and velvety, but the difference in their relative cost is very wide, and the writer will not undertake to say how far the marketable value of the goods is improved, but thinks it will be admitted that their intrinsic value to engineers is not altered in any way.
I may here observe, that carbonates work best in all moulded goods, but not otherwise, and it is necessary they should be retained therein until quite cold, or they swell out of shape; but in packing, &c., vulcanized openly, oxides should be selected, as there is little or no chemical action with sulphur or heat. I have made no mention in these papers of very finely pulverized talc, or French chalk, which, from its cheapness, if well bought, and its being unaffected by heat, and its slippery nature, is invaluable as a top dressing, well rubbed in, upon the surface of all white goods for open vulcanizing, as well as dusting the sheet zinc upon which they are laid. It is equally valuable in all goods cured in rolls, such as medical sheeting, &c., and renders entirely unnecessary the rays of the sun afterwards, needing only to be wiped off with a dry cloth after vulcanizing.
There are many most respectable manufacturers, and these should have their sense of honorable integrity acknowledged, and, as far as possible, be protected from their inferiors in morality. In writing these papers off hastily, one is really tempted to get into aviolent rage with this vicious system; especially when one calls to mind that, no sooner does an ingenious man invent something really valuable and useful, but these kidnapping and adulterating traders counterfeit the same instantly, and render their make to all appearance (and to the unsuspecting) equally good, though, in reality, not so, being merely cheapened by this adulterating and tricky system. Added to which, if the originator is not very sharp in obtaining his protection for the really valuable service he has rendered to science, and to the sale of which he is looking very naturally and justly, as a remuneration of what may have probably cost the inventor many days and nights of weariness, and possibly involved the spending of his money capital, and perhaps, even besides, months of labor, disappointment, poverty, and sorrow, I say, if he is not very quick in his protection, the unblushing effrontery and impudence of these “second hand people” will rob him of the whole. I believe no pen can sufficiently protest against those individuals who thrive “and make haste to become rich” from the oozings of other men’s brains. Theirs is the basest class of felony our laws cannot reach, and, consequently, their infamous and nefarious habit continues unheeded and untouched, and often (because unknown) unscorned. This applies to caoutchouc. Special reference to particular manufactures must be discussed another day; but, if I am rightly informed, Mr. C. Goodyear especially, and others, to some extent, have suffered from these copyists very egregiously and seriously. Though my testimony would be confirmed by our best men in every branchof trade, where there is scope for genius. I must not digress, and trust you will excuse my hasty protest against thiscounterfeit coin.
I will therefore, at once, hand you the formula for
This costs about 13 cents per lb., and is sold at 50 cents per lb., and, as you will perceive, contains about 110 per cent. of adulterating matter. Considering the mass of foreign substances in the above formula, (and yet sold under the name of “caoutchouc,” whichshould be pure Java gum, of less than half the density, for a great deal less than 50 cents gross price), one is almost astonished that the “gum-elastic” should retain any of its original liveliness, mixed up with so much dead weight; but so it is, as I shall show, by stating that a buffer-ring (4½ × 2½ × 1 ins.) of this quality exactly, and of the same size as those of which I gave the tonnage in your Magazine of the 24th of October, indicated, on the same being pressed to half an inch, 4½ tons on the dial. Of course the weight of the ring was fully double those then remarked upon, arising from increased density by adulteration. Pursuing the same subject of density, I have observed that these manufacturers have been compelled to chargeless than the actual weightof their goods, as the people at Berlin would not pay caoutchouc price for so much rubbish. This in the“good old red-lead time,” when the manufacturers, with more faith than judgment, considered they could not include too much of that metal, but they have since become more crafty and subtle, and use it less madly. I weighed a cylinder or spring some few months since, of which a like quantity are now in use by the London and North-western Railway, and, I expect, at their station at Wolverton, which contained at least, 100 to 130 per cent. of cheap, heavy adulteration; and yet they paid 1s. 6d. per lb. in quantity nett. The size was 6½ × 2½ × 4, and weighed close upon 6 lbs. I should say, if the charge had been 9d. per pound, no manufacturer could need a better trade, hence I have chosen to throw a little a “free trade light” upon the subject.
The washer trade is a very lucrative one to the manufacturers, being principally cut from the spare or waste ends unavoidable in the make of springs, cylinders, and buffer-rings.
I will now give you the formula for what is termed
Costing about 12½ cents per pound.
Sometimes the Para gum is used in this mixture; but, though better, its use is not considered imperative if the Java caoutchouc is well cleansed. A cured coat, well vulcanized, is a great improvement in all respects upon the filthy naptha or varnishcoat, and should, when competition is thrown into the market, exceed it very little in charge. As long as the calico upon which these are run is covered, the thinner that covering the better; and by far the best I have seen are made by Messrs. Mackintosh and Co., Moulton & Co., Moses, Son & Davis. I have seen some very bad ones, ill-shaped, non-vulcanized, and altogether only usefulin bringing the better make into unjust dislike by the public. The sooner these latter daubs are improved, or withdrawn from sale, the better for the reputation of the India-rubber garment dealers. The cloth upon which the material is spread weighs about four ounces by the yard, and therefore the quantity of gum on each article is readily assessed, and the scale will determine which are lightest and best for a storm.
The article termed “sulphuret of lead” in the formula, is the chemical I have before remarked upon, and the screen or blind, nick-named (for reasons therein explained) “hypo,” and is only useful in so far asit is an excellent black pigment, which is only of importance in the garment branch of the trade.
There is no necessity for the monstrous charges at present made for these goods, and hence I desire to open up the subject fearlessly. The amount of adulteration necessary to bring up the desired color, is from 4 to 10 per cent. of the pigment termedoxide of zinc; but the formula used for the manufactureof the water or air mattresses and cushions referred to, contains aboutthirty-five per cent. of this cheap substitute for India-rubber. In writing thereon I take leave to state at the outset, that, like the “air,” or Mackintosh cushions or pillows we have known for so many years, they can be had of any size or shape, and differ from them in being of pure caoutchouc, or elastic gum, (minus the adulteration) instead of only athin coatingof pure gum, upon a cloth or non-elastic foundation. Hence their increased value to medical men in preventing bed sores, &c.
In my judgment, what is understood in these days by the word “humbug,” has gained such ascendancy over common sense, that honorable people, who disdain to practice it, are so out-distanced by the many who do, that they lose thereby several of the chances of trade. This “popular pet humbug” is, therefore, largely dealt in by puffing advertisers (even in these articles) who perpetually issue illustrated catalogues, &c., under the word “patent,”where none exists, “Improved Hydrostatic Water Mattresses,” “Inventor” and “sole manufacturer,” and a host of other fanciful and attractive names, through our Post Office, to the whole medical profession in the United Kingdom, as well as to the staff of medical men connected with all the Hospitals, Poor Law Union Infirmaries, East India and other companies, &c., and these mattresses are now in use at most of such establishments; and if the retail prices were not highly extortionate, and altogether beyond all reasonable limit, I would not throw the “sunshine” upon this valuable medical appliance.It just strikes my memory that there is a quiet notification in the interior of the envelopes of these circulars, that a discount of 12½ per cent. is allowed to the “profession,” (but which some refuse.) I may as well add, that these dealers, of course, haveno exclusive rightto the above names, as they would lead the public to infer,the manufacture being as free as the air we breathe; and of “hydrostatics,” they understand about as much as they do about general “chemistry,” and I am quite sure that of the latter exquisite science they know only just as much as the letterer can actually embody and make inherent in the words he may be instructed to paint on the door posts or facia outside. It is a melancholy truth, that this lettering is now accepted as proof that the “professor”inside, is in fact, a “practical” or “operative chemist,” though he may live and keep shop at the west end of the metropolis, and exhibit a framed notification, that he is a member of the “Pharmaceutical Society of Great Britain,” but without examination.
It is incredible, moreover, how these people, by their presumption, even seem to deceive medical practitioners, judging from the numerous “good names” they append to some of their valueless compounds ofexhausted roots. In many cases beyond the capacity of informing an enquirer why, in “camphorated spirit” the addition of “water” precipitates free camphor, (to use a figure) they know no more of chemistry than the writer’s “foot;” and yet if one had not daily experience and proof that true science is modest and retiring, one would be liable to put these “professors” down as real living “Faradays,” “Herapaths,”“Redwoods,” and other equally illustrious chemists instead of quacks. Excuse the digression, but these characters who disgrace an intellectual science, will cross one’s mind in writing.
Returning to the water mattresses, I will show in figures, in the manufacturer’s price in 1850, and the manufacturer’s charge in May, 1856, (and it must be less at this moment,) and the uniform retail price, and to this latter I invite the special attention of your readers, and ask them carefully to note theretailer’s profiton each, and decide the advantage to be derived from purchasing of the manufacturer. I have no personal interest in any of them. I will show also their usual sizes, and their weight, as they are all sold by the manufacturers, on this basis.
I trust this may stir up increased demand for so useful and necessary an article for the alleviation of human suffering, the use of which theimmense retail profits have hitherto prohibitedamong the middle and humbler classes.
The formula for water mattresses and cushions—(India-rubber) is:—
This is the price per pound the weight should be estimated at. The mattresses vary in size from 8 + 14 inches to 48 + 72—some with cells—some without cells. Theretail profitson these goods, over the manufacturer’s prices, in 1856, ranged from 13s. 6d. to £7, 6s.—according to the size of the mattress. Or in American currency, from about $3.00to $36.00 profit on single mattresses.
Should so serviceable an article be thus clogged and fettered by such immoderate charges by the retail shop-keepers? It may probably be a guide to some of our readers to state, the best size pillow is 17 + 22, and that the celled mattresses 27 + 30, and 30 + 40, are found most useful, and of adequate length to support the trunk of invalids, and admit the other portion of the body to rest upon the usual feather bed, and thus steady a weak patient; as a full length mattress of elastic gum, 33 + 72 is beyond the safe control of such invalids.
The retailer, for obvious reasons, recommends the larger mattresses, and which arenotreturnable,even if the patient dies before they reach him.
CHAPTER VI.VALUABLE RECIPES, ETC.PURIFYING GUTTA-PERCHA.
H. H. Day, of New York, has obtained a patent in England for extracting from gutta percha a peculiar etheric oil which it contains, preparatory to its being subjected to the process of vulcanization, by submitting it to the action of a liquor which dissolves out the etheric oil, and also, at the same time, by acting upon the woody matter, disengages the sand or other foreign substances held therewith. This liquor is composed of caustic potash (hydrate of potassa) dissolved in water, with an ether formed from a solution of chloride of lime and alcohol added, and after the crude gutta-percha is placed therein the whole mass is heated to a boiling point, and so kept for about nine hours, and then treated between rollers under water, in the ordinary manner. When taken out, the gum will consist of a pure and solid mass, resembling India-rubber, and fully equal to it in fineness, and in the readiness with which it may be worked to prepare it for the additional process of vulcanization.
PURIFICATION OF GUTTA-PERCHA,
By James Reynolds, of New York City. Gutta-percha, in the raw state in which it is imported, contains large quantities of bark, dirt, and foreign substances. In the common processes of manufacture these cannot be extracted, and bad results often ensue. For example, in the covering of telegraph wires, holes are often left wherever foreign substances are present, and thus the insulation is impaired. The only method heretofore employed, for preventing the quality of the manufactured article from being too much injured by the presence of these impurities, has been to reduce the bark and dirt into fine particles, by long-continued and tedious grinding, and then incorporating them with the gum.
The object of the present improvement is to effect the entire extraction of the bark and other foreign particles, and thus improve to a very great degree the quality of the manufactured article. The invention consists in first cutting the gutta-percha into extremely thin slices or sheets, and then submitting it to heating, rubbing, and screening operations. Under this treatment the foreign matters, are almost entirely extracted, and the gutta-percha left pure. This is a valuable invention.
Take one pound of India-rubber and then dissolve it in the exact quantity of naptha, or oil of tar to render it moderately thin, (about a gallon) to which is added shellac, and the whole allowed to maceratefor ten days, until it attains to a cream like consistency. After which more shellac is added to make it pretty stiff, when it is heated and then poured out into plates. It is heated to 250°, when applied. The mixture is that of India-rubber and shellac dissolved in naptha. It is insoluble in water and not affected by the heat of the sun.
In Paris a new kind of cuirass for the use of the army, is shortly to be tried. This cuirass is of vulcanized India-rubber, about half an inch thick. The thickness, it is stated, is more than sufficient to resist the action of a ball projected from any kind of firearm. All the experiments tried have proved entirely successful. The force of the ball is completely broken by the elasticity of the India-rubber, and it falls on the ground at the feet of the person against whom it was sent.
Alfred H. Gaullie, Paris, patentee. This improved composition is formed by mixing together equal parts of gutta-percha and of Roman cement reduced to a pasty consistence with ox-gall. The operation of mixing is to be performed while the gutta-percha is in a heated and plastic state, and the two ingredients must be well masticated so as to cause them to combine intimately together. Any kind of coloring matter may be combined with the materials according to the effect desired to be produced.