Treatise _on distilling_ Sea-Water, _sweetning_ Milk, _&c. which gives
a farther Account how to procure still greater Plenty of_ Fresh-water
_at 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 of _Peter Wyche_, Esq; in a Still
containing 24 Gallons of Water, at Messrs. _Steel_ and _Stephens_’s
Copper Workhouse, near the _Falkon-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 the first Air-box was 18 + ½ Inches. On
three several Trials, a _Winchester_ Quart 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
it was 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 the
_Falcon-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 in of
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 ventilate while 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. _Wyche_ thought 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 the _Health and
Lives_ of 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 the _Prince_ of _Wales_ and _Prince Edward_, viz.
“That in the Year 1753 Ventilators were put into the Vessels in the
Slave Trade at _Bordeaux_, and in other Ports of _France_; the happy
Effect of which was, that instead of the Loss of one-fourth of those
valuable Cargoes, in long Passages from _Africa_ to the _French_
Plantations, the Loss seldom exceeded a twentieth. And since my Return
to _England_, I have been informed of a _French_ Vessel, 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, dated _Charles-Town, South-Carolina, March_
24th, 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 from _Africa_, (even though they call for fresh Provisions
and Water at the _Islands_) 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 of _March_ the 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;
and with 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 of _June_, 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 eating _Crow-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 the _Crow-Garlick_ Milk, 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 the _Crow-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 recompence the 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 in _Cranbourn-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 of what 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 in
_Farenheit_’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 Pail
_A_ in two Gallons of fresh Pond-Water, thro’ which a Stream ran, and
twelve more into a Pail _B_, with the like Quantity of Water; one of
which Fishes in _B_ was sick, as appeared by turning its Belly upwards;
as were also two Fishes in the Pail _A_, which was occasioned by being
all brought in a Pail above half a Mile from the _Thames_.
91. At 45 Minutes past 8, most of the Fish in the Pail _B_, 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 in _B_; 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
Pail _A_; and a like Number into a Pail _B_, at 10 Minutes before 7
in the Morning. At 50 Minutes past 7, two in _B_ began 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 in _B_, 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 Pail _A_ was ventilated from 10 Minutes before
7, to 6 in the Evening, by blowing 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
of Land 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
the Water 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.
_FINIS._