AN APPENDIX TO THE
Treatiseon distillingSea-Water,sweetningMilk,&c. which gives a farther Account how to procure still greater Plenty ofFresh-waterat Sea, and to sweeten ill-tasted Milk, Stinking-water, and musty Liquors, &c.by blowing Showers of Air up thro’ them.
Treatiseon distillingSea-Water,sweetningMilk,&c. which gives a farther Account how to procure still greater Plenty ofFresh-waterat Sea, and to sweeten ill-tasted Milk, Stinking-water, and musty Liquors, &c.by blowing Showers of Air up thro’ them.
74. Several considerable Improvements having been made on the Subjects of this little Book, since the Publication of it, I shall here give a short Account of them, hoping they may in several Respects be of Benefit to the World; especially the great Improvement in distilling Plenty of Fresh-water at Sea.
75. In order to bring the Method of procuring Plenty of good Fresh-water at Sea, into practice, several previous Trials were made, at the laudable Motion and Desire ofPeter Wyche, Esq; in a Still containing 24 Gallons of Water, at Messrs.SteelandStephens’s Copper Workhouse, near theFalkon-Stairs, Southwark. The first thing to be done, was to find out the proper Size of the Diameter of the Copper Air-box. The Diameter of the Still, near its Bottom, being 19 Inches, the Diameter of thefirst Air-box was 18 + ½ Inches. On three several Trials, aWinchesterQuart of Water was distilled in five Minutes by the common way of Distillation; and by Ventilation a Quart was, in 3 or 4 Trials, distilled in 2 Minutes; but at the Distillation of the ninth Quart, the Water was so much cooled by the ventilating Showers of ascending Air, as to require 5 Minutes and 44 Seconds. Now this great Decrease of the Quantities distilled, was plainly owing to the too great Breadth of the Air-box, which hindered the Fire from heating and keeping hot the Water which was above it, to such a Degree, as to have no Distillation in the common way, for 8 or 10 Minutes after the Ventilations; for the half Inch Circle of Water which was not covered by the Air-box, was but one nineteenth Part of the whole. The next Trial, in the same Still, was made with an Air-box, whose Diameter was 13 Inches, its Area therefore 127 square Inches; which deducted from 271 square Inches, the whole Area or Breadth of that part of the Still, there remains 144 square Inches, for the Area of the three Inch broad annular Circle round the Air-box,viz.17 square Inches more than the Area of the Air-box. The Event was, that in seven Distillations in the common way, a Quart was distilled in 5 Minutes, sometimes in a little less, and sometimes in a longer Time. And by Ventilation 14 different Quarts were distilled in different Lengths of Time, from a Quart in 2 Minutes and 6 Seconds, to 3 or 4 Minutes.
76. I then repeated the like Trials with my small three Gallon Still, distilling in the common way a Pint in 10 + ½ and 9 Minutes; and seven separate Pints were distilled by Ventilation in 3 + ½ to 4 + ½ Minutes. Hence we see that Ventilation has a more steddy and constant good Effect where the Air-box is less in Proportion to the Still, than itwas in the other two Distillations: For in this lesser Still, only 27 out of 99 square Inches were ventilated, 72 square Inches being unventilated. It will therefore probably be advisable to have the Air-boxes of other Stills to be nearly in the like Proportion to the respective Stills, the Diameter of this Still being 11 + ½ Inches, of its Air-box 6 Inches.
77. As by repeated Trials a Quart of Water was distilled in the common way in five Minutes, in the above-mentioned twenty Gallon Still, so an 120, or two Tuns and 14 Gallons, may be distilled by Ventilation in twenty Hours.
78. Mr.Wyche, who was present at the Trials near theFalcon-Stairs, observing the Water in the upper Part of the Worm-tub to be reeking hot, tho’ the Water below it was cool, very rightly proposed to have the hot Water run from the upper part of the Worm-tub, thro’ a small Copper Pipe, into the upper Part of the Still, as fast as it was distilled off, the running Quantity of Water to be adjusted by a Turn-cock in the Pipe. This I tried in my little Still, by conveying the upper warm Water of the Worm-tub into the Still thro’ a small Pipe Which passed thro’ a Hole in the Head of the Still, almost down to the Bottom of the Water in the Still: My Reasons for doing of which were,viz.lest the less hot Water, by running on the Surface of the boiling Water, might considerably check the Ascent of the rising Vapours; whereas, being mixed and blended with the lower Water, it will soon acquire a due Heat. Another Reason why I chose to lead the entering Rill of Water so slow, was, that it might be intimately mixed with the Chalk, which is there in an agitated State by reason of the Action of the Fire. The Event was as follows,viz.that six separate Pints of Water were distilled by Ventilation during the running inof the warm Water, some in 3½ Minutes, others in 4 Minutes, 4 + ½, and 4 Minutes, 50 Seconds, which was the case of the second Pint.
79. Hence we see the great Benefit of this ingenious Improvement of Mr.Wyche’s in distilling Sea-water, where the Still will be filled with the same Liquor as the Worm-tub; but this Method cannot so well be put in Practice in other Distillations. The Benefit of thus gently and incessantly keeping the Still full, will save about one-fourth of the Time and Fuel, which it would otherwise require to refill with cold Liquor, and bring to a distilling Heat. This great Advantage, added to that of distilling about double the Quantity by Ventilation, must needs both together be of so great Improvement in distilling three Parts in four more than usual, as will be of the greatest Benefit to Navigation in several respects. By this means the Still need be emptied and cleansed from the Chalk, and very salt Water, only at the end of each daily Distillation.
80. And whereas if all the Chalk requisite for a whole Day’s Distillation were put into the Still at once, it might be suspected that such a Quantity laying at the Bottom of the Still, might hinder the boiling of the Water: I put into a broadly flat-bottomed sauce-pan, half an Inch Depth of powdered Chalk, and two Quarts of Water boiled in ten Minutes: The Water mingling freely, especially in the time of boiling, among the thin pappy Chalk, was freely acted on by the Fire. But as in boiling it frothed much, it may be proper to put at first into the Still only as many half Ounces of Chalk as there are Gallons of Water; and afterwards from time to time in proportion to what additional Water shall have run into the Still, at a Hole purposely made in the Head of the Still, taking care to ventilatewhile the Chalk is putting in, which will cause it to mix intimately with the Water, and thereby have the better Effect on it. And perhaps a less Proportion of Chalk than half an Ounce to a Gallon of Sea-water may suffice.
81. The Degree of Fulness or Emptiness of the Still, may be known by putting a small floating metalline Vessel, in at the Chalk Hole, with a long slender Wire to it.
82. Mr.Wychethought of other Means the better to promote Distillation,viz.by conveying the Air from the Bellows through a Pipe with several spiral Coiles, thereby in passing thro’ boiling Water in the Still, to make the ascending Showers of the Air the hotter, and so the less refrigerating. Also to have the warm Water pass from the Worm-tub, in a Pipe, with several the like spiral Coiles, in the Head of the Still; thereby the more to heat the entering Water. But we find, by the above-mentioned Experiments, that there is no occasion for either of them; but if wanted may be used.
83. As to the Benefit of Ventilators in preserving theHealth and Livesof People in Slave and other Transport Ships, I have received farther Confirmation of their great Benefit, in a Letter from Dr.Demainbray, who has shewn Courses of Experimental Philosophy to his Royal Highness thePrinceofWalesandPrince Edward, viz. “That in the Year 1753 Ventilators were put into the Vessels in the Slave Trade atBordeaux, and in other Ports ofFrance; the happy Effect of which was, that instead of the Loss of one-fourth of those valuable Cargoes, in long Passages fromAfricato theFrenchPlantations, the Loss seldom exceeded a twentieth. And since my Return toEngland, Ihave been informed of aFrenchVessel, which by this self-evidently reasonable Precaution, saved 308 out of 312 Slaves, spite of most tedious Calms and a long Passage.” And Dr.Garden, in his Letter to me, datedCharles-Town, South-Carolina, March24th, 1756, says,viz.“It is indeed very wonderful, that the Slave Merchants do not come into the Use of Ventilators. There are few Ships come here fromAfrica, (even though they call for fresh Provisions and Water at theIslands) but have had many of their Cargoe thrown overboard; some one-fourth, some one-third, some lose half; and I have seen some that have lost two-thirds of their Slaves. I have often gone to visit these Vessels on their first Arrival, in order to make a Report of their State of Health to the Governor and Council; but I never yet was on board one, that did not smell most offensive and noisome. What from Filth, putrid Air, putrid Dysenteries (which is their common Disorder) it is a wonder any escape with Life.”
84. A probable Means lately occurred to my Thoughts, tho’ not perfectly to cure, yet much to abate the great Degrees of stinking of the Bilge-water in the Well of Ships,viz.by laying at the Bottom of the Bilge-water, round the Main-mast, Copper Pipes full of very small Holes, not one twentieth of an Inch in Diameter; and blowing Showers of Air up thro’ them from small Black-smith’s Bellows, fixed out of the way, within the Well. Such Bellows may be worked with great Ease, for one, two, or three quarters of an Hour, in every 24 Hours, more or less, as shall be found requisite by Experience: But with this Precaution, that whenever the Water stinks much, first to pump it out of the Ship, and after letting in sweet Water,then to ventilate it a little now and then, as shall be found needful; but care must be taken not to ventilate very stinking Water, because it may increase the Unwholsomeness of the foul Air in Ships. By this means Ships will probably be made something less unhealthy; for the putrid Vapours which arise from stinking Water, must needs greatly contribute to increase the Putridness, and consequently the Noxiousness of the foul Air in Ships. This Precaution therefore, with Ventilators frequently to convey off the close foul Air, will be effectual Means to make Ships much more healthy; as will the changing the foul Air in Goals, Hospitals, and sick Rooms, with proper Precautions, make them more wholsome: And it is with pleasure that I observe, that these salutary Means are coming more in use in Hospitals,&c.either by means of Ventilators, or by admitting fresh Air in small Quantities, and those spread in thin Sheets, so as not to have the entering Air blow directly on, and incommode the Patients. Where it can be had, a thorough Air entering on one side, and passing out on the other side of Wards or Rooms, will be best; because the Change will be almost constant, and may be as gradual and gentle as we please. I shall give a more particular Account of this in my second Volume of Ventilators.
85. As to the curing the ill Taste of Milk from the Food of Cows; and also curing musty Liquors, I made the following Trials,viz.When in the Beginning ofMarchthe Turnips had made large Shoots, and were thereby become very rancid, two Cows being fed with Turnips only for seven Days, their Milk had a very disagreeable Smell and Taste. On ventilating it scalding hot, with ascending Showers of Air, at first the ill Smell increased, but in two Minutes that Smell was much abated; andwith five Minutes Ventilation, there was only the common Smell of good Milk; which shows that the rancid Oil of Turnips, which gives the ill Taste, is very volatile: After ten Minutes Ventilation, there was no ill Taste or Smell; and it was the same after 15 and 30 Minutes Ventilation. By this means therefore the ill Taste of Milk from some Food of Cows, may easily be cured. Experience will show what Degrees of Ventilation will be requisite for larger Quantities of Milk; as also for curing the ill Tastes from different Kinds of Food; as also from the shorter and longer Times of feeding on such Foods. It is observable that the Breath of these Cows was disagreeable; whence we see how freely contagious Infections may be conveyed through the Lungs, from tainted putrescent Blood.
86. A Cow having been fed for sixty Hours with a good Quantity of Crow Garlick, mixed with cut Grass, towards the end ofJune, the Milk had a very disagreeable Smell and Taste; which was not cured, though something better, after 30 Minutes Ventilation, while scalding hot. I repeated the same Ventilations for 15 Minutes, with the two following Evening and Morning Milks of the same Cow,viz.12 and 24 Hours after the Cow had left off eatingCrow-Garlick; at which times the ill Taste and Smell was sensibly abated before Ventilation, and something more after it, yet was far from being cured. Hence we see that the ill Taste and Smell of theCrow-GarlickMilk, cannot thus be cured, tho’ somewhat amended. The ill Taste of this Cow’s Milk continued for about five Days after she had left off eating of theCrow-Garlick. And perhaps where Cows have eaten but a small Quantity of it, the Abatement of the ill Taste may be so considerable, as to recompencethe Trouble of ventilating it. As Opportunities offer, I will make the like Trials, with other ill-tasted Milks, such as that from autumnal Leaves,&c.and hope that others will do the like.
87. Cream or Milk Sillabubs may most commodiously and easily be made in Plenty, in a few Minutes, by means of a small Tin Air-box, three Inches in diameter, and three quarters of an Inch deep; the flat Bottom of the Pot, which contains the Cream or Milk, to be but little wider than the Air-box, that the Air from the Box may the better come at it: But the wider and deeper the upper Part of the Pot is, so much the better, for the Froth expands much.
88. Scalding-hot musty Vinegar was cured by repeated Trials, of near three Gallons in each Trial, by ten Minutes Ventilation. And giving Vinegar a scalding Heat, does not weaken or damage it, as it does Wine, whose vinous Spirit is carried off both by Heat and Ventilation; for when some strong musty Raisin Wine was ventilated hot, it was cured in five Minutes: But the vinous Spirit, which strongly affected the Nose in flying off during Ventilation, being gone off, the vapid Wine would not kindle into a Blaze, when thrown into the Fire, as it did to a great Degree before it was heated and ventilated. Neither musty Wine nor Vinegar were cured, tho’ something bettered by 30 Minutes Ventilation, when cold.
89. Mr.Jones, a Chemist inCranbourn-Ally, Leicester-Square, ventilated a Gallon of Proof Malt Spirits 15 Minutes cold, in which time it wasted two Ounces and half; whereas a like Quantity of common cold Water wasted but half an Ounce in 15 Minutes Ventilation,viz.but one-fifth part ofwhat the Spirits did; and the same Spirits ventilated hot, wasted no less than 5 Ounces in 5 Minutes; which Ventilation made them sensibly better tasted than the unventilated. But the great Waste shows that these volatile vinous Spirits, ought not to be ventilated, neither hot nor cold. Besides that, the 15 Minutes cold Ventilation had but little Effect in bettering the Spirit.
90. In order to know whether Fish in a Vessel of Water would live the longer for having Showers of Air blown up thro’ the Water,May 25, 1756, at seven in the Morning, the Wind N. E. the Mercury inFarenheit’s Thermometer, 50 Degrees, and it continued so cold, that at one o’clock it rose but to 60 Degrees; I put twelve Dace into a PailAin two Gallons of fresh Pond-Water, thro’ which a Stream ran, and twelve more into a PailB, with the like Quantity of Water; one of which Fishes inBwas sick, as appeared by turning its Belly upwards; as were also two Fishes in the PailA, which was occasioned by being all brought in a Pail above half a Mile from theThames.
91. At 45 Minutes past 8, most of the Fish in the PailB, were turned Belly upwards, and lay as dead; at 30 Minutes past 9 seven of them were dead; at 30 Minutes past 11 all but three were dead; at two o’clock but two Fish remain alive inB; which remained alive, tho’ sick, at ten that Night,viz.at the end of 14 Hours.
92. The good Effect of blowing every quarter of an Hour, with 25 Strokes each time with double Bellows, Showers of fresh Air up thro’ the Water, was,viz.they all continued well, and the larger of the two sick Fish recovered; but the lesser died at 4 o’clock,viz.at the end of nine Hours;upon each Ventilation it turned its Back upwards; but soon after the Ventilations, it constantly fell precipitate with its Head foremost, to the Bottom, and there turned Belly upwards. After 4 o’clock the ventilated Water frothed with larger Bubbles, this owing to the Slime of the Fish. The last Ventilation was at 10 at Night, when the Fish in the ventilated Water were well, and would probably have long continued so by the Salutariness of Ventilation; but that being discontinued, they were all found dead the next Morning, except one which had some small Degree of Life.
93.June 7, the Wind S. W. cloudy, the Thermometer at 58 Degrees, 13 live Gudgeons were put into two Gallons of fresh Pond-water in a PailA; and a like Number into a PailB, at 10 Minutes before 7 in the Morning. At 50 Minutes past 7, two inBbegan to be sick; at 8, half of them came up for Air, and showed Uneasiness; at 15 Minutes past 8 two are dead; at 30 Minutes past 8, eight more turned Belly upwards; at 8 Minutes past 9, five are dead inB, and five more sick; at 30 Minutes past 9, seven are dead, and four sick, two well; and 30 Minutes past 10, eight are dead; at 11 two only alive, and also well, though they showed some Uneasiness by their raising their Mouth to the Surface, which they continued to do till nine, when they were taken out of the Water. Hence we see, by this, and the preceding Experiment on Dace, that one or two Fish may be kept alive many Hours longer than a greater Number can be, by means of the small Portion of fresh Air, that is continually mixing with the Water, on which it presses.
94. The Water in the PailAwas ventilated from 10 Minutes before 7, to 6 in the Evening, byblowing every quarter of an Hour Showers of fresh Air up thro’ it, with 25 Strokes of the Bellows; by which means the Fish continued all well, laying quiet at the Bottom: At six we ceased to ventilate; for an Hour and half after which, there was no Signs of Sickness, after two Hours two of them showed Signs of Uneasiness; and at nine most of the Fishes turned Belly upwards, and lay at the Bottom dead or dying. By comparing this Event with that at eight in the Morning, we see there is more Air in this ventilated Water than in the Pond-water, as is probable by the Gudgeons living longer in it without Ventilation, than in the Pond-water. And accordingly the specific Gravity of unventilated Pump Well-water, was a very small Matter greater, than that of the same, after being ventilated with 100 Strokes of the Bellows, as I found by the Hydrometer; and there was nearly the same Difference between the specific Gravity of unventilated and ventilated Table Beer.
95. Tho’ from these Experiments it is manifest, that Fish die for want of constant Supplies of fresh Air in the Water, yet when taken out of the Water very lively, they soon die, notwithstanding the Surfaces of their Gills are then exposed to the immediate Contact of the Air; which shows that either the Air does not enter from the Gills to the Blood, from the open Air, as it does from the Water; or that the Circulation of the Blood is stopped by exchanging their proper Element, Water, for Air; as the Circulation of the Blood of Land Animals is soon stopped by immersing from Air into Water.
96. Hence we see the Benefit of frequently replenishing the Water with fresh Air, which we find is necessary not only to preserve the Life ofLand Animals, but also of Fish; as also the Use of their Gills, to spread in thin Sheets fresh Supplies of Water, that they may the better come at the Air in the Water; for which Purpose both Sides of their Gills are furrowed with many fine Furrows, not only thereby to enlarge their Surfaces, but also more minutely to divide the Water, whereby to come at the Air in it.
97. Whence we may reasonably infer, how requisite it is, in order to keep the Blood in a salutary State, to have almost constant Supplies of the Breath of Life, fresh Air, to mix with it: For if the principal Use of the Gills were only to cool, and churn, and comminute the Blood, Water devoid of Air could as well perform that Office, as Water repleat with fresh Air. It must therefore be of Importance for all Animals to have so necessary a vital Fluid fresh and pure, and not foul and putrid.
98. A Fisherman informing me that the Fish were apt to die in the Well-boats, it occurred to me that it might, in a good measure, be remedied, by fixing upright a Board of a proper Breadth at the Outside of the Boat, as long as the Well is deep, on that side of the Well which is next to the Stern, and opening at an Angle of about 45 Degrees towards the Head; which, by checking the Course of the Stream of the River near the Boat, will raise the Water a little, and thereby cause it to run into the Well on that Side, and out on the other Side of the Boat; and the Run of the Water thro’ the Well, will be more accelerated, if a like Board is fixed in the same manner on the other side of the Boat at the Side of the Well next to the Head of the Boat, but opening towards the Stern at an Angle of 45 Degrees, by which means theWater will be lowered on this, as much as it is raised on the other Side of the Boat.——Another Means to have a brisker Current of Water thro’ the Well, would be to moor the Boat in a fixed Position across the Stream when it can conveniently be done. I am informed that there are Passages from Head to Stern, for the Water to pass freely thro’ the Fish-Well of some Vessels. We see, from the Event of the above Experiments, the Importance of frequently changing the Water in the Fish-Well of Ships, especially when there are many Fishes in it. Hence also we see how salutary it is to Fish, to have the Surface of the Water agitated into Waves by Winds, whereby Plenty of fresh Air enters, and is blended with the Water.