Full resolution (JPEG) - On this page / på denna sida - Pages ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
588 PHIPPS § JOURNALs
highly heated, paffing over fo much furface of metal, viz. the flill-head, ¢rane-neck,
anda pipe of fix or {even feet in length, beforeit reaches the water in the worm tub.
“© Having difcuffed the fubje@ of diftillation, we come now to treat of the chemical
analyfis of fea water.
‘© Sea water contains chiefly a neutral falt, compofed of foffil alcali and marine acid.
It likewife contains a falt which has magnefia from its bafis, and the fame acid. Thefe
two falts are blended together in our common falt in England, which is prepared by
quick boiling down fea water. But when the procefs is carried on by the fun, or a flow
heat, they may be collected feparately ; that which has the foffil alcali forits bafis cryf-
tallizing firft; and this is of a vaftly fuperior quality for preferving meat, and for the
other culinary purpofes. The mother liquor now remaining, being evaporated, affords
a vitriolic magnefia falt, which in England is manufactured in large quantities, under
the hame of Epfom falt.
“< Befides the falts, which are objects of trade, fea-water contains a felenitic falt,a
little true Glauber’s falt, often a little nitre, and always a quantity of gypfeous earth
fufpended by means of fixed air. E
“‘ The fpecific gravity of fea water to that of pure diftilled water, is at the Nore as
1000 to 1024,6; in the North feaas 1e00 to 1028,02.
« The quantity of falt obtained by boiling fea-water in different latitudes, from
51° 30’ to 80°, 43 N. L. appears from a table in the original work.
“© Sea-water, when boiled down to a {trong brine, admits with difficulty the fepara-
tion of frefh water from it ; the diftillation becoming flower as the ftrength of the brine
increafes, fo that agreater quantity of fuel is confumed in procuring a f{maller portion
of watér, and this likewife of a bad quality. From this effential circumftance arifes
the neceflity of letting out the brine by the cock of the boiler, when the diltillation is
advanced to a certain degree; and of adding more fea-water to continue the procefs if
required,
Xe The defeéts of the feveral fchemes formerly propofed for rendering fea-water frefh
being pointed out, the general principles of diltillation explained, and the component
parts of fea-water analytically examined; the advantages of the method invented by
Doétor Irving remain to be ftated, which may be reduced to the following :
“a, The abolifhing all ftills, {till heads, worm-pipes, and their tubs, which oc-
cupy fo much {pace as to render them totally incompatible with the neceffary bufinefs
of the fhip; and ufing in the room of thefe, the fhip’s kettle or boiler, to the top
whereof may occafionally be applied a fimple tube, which can be eafily made on board
a veffel at fea, ofiron plate, ftove funnel, or tin fheet ; fo that no fituation can prevent
afhip from being completely fupplied with the means of diftilling fea-water. -
“2, Inconfequence of the principles of diftillation being fully afcertained, the cons
trivance of the fimpleft means of obtaining the greateft quantity of diftilled water, by
making the tube fufficiently large, to receive the whole column of vapour ; and placing
it nearly in a horizontal direction to prevent any compreflion of the fluid, which takes
place fo much with the common worm.
“* 4, The adopting the fimpleft and moft efficacious means of condenfing vapour ;
for nothing more is required in the diftillation but keeping the furface of the tube al-
ways wet; which is done by having fome fea-water at hand, and a perfon to dip a mop
or {wab into this water, and pals it along the upper furface of the tube. By this opera-
tion the vapour contained in the tube will be entirely condenfed with the greateft rapi-
dity imaginable ; for by the application of the wet mop thin fheets of water are uniformly
fpread, and mechanically prefled upon the furface of the hot tube; which being ous
; 10, verte
<< prev. page << föreg. sida << >> nästa sida >> next page >>
