Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 19, Scripture-SUG

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jecific that the brine fl-iould be weak 5 for the differences of
ravity* fpecific gravity go on diminifhing in the ftronger brines :
^ “ 300 ounces of dry fait diffolved in 897. ounces of water
ihould give the fpecific gravity 1197. Suppofe it be
but 1190, tile quantity of fait correfponding is only
290 ; but when mixed with 897 ounces of water, the
weight is 1x97, although the weight of the cubic foot
is only 1190. There is therefore more than a cubic
foot of the brine, and there is as much fait as will make
more than a cubic foot of the weight 1190. There is
1197
290 X Tup’ °r 29it ouaces> ancl there is 8-f ounces of
water attached to the fait.
The various informations which we have pointed out
as deducible from a knowledge of the fpecific gravity of
the brines of common fait, will ferve to fuggeft leveral
advantages of the knowledge of this circumftance in
other lixivia. We (hall not therefore refume them, but
limply give another table or two of fuch as are moll: in-
terefling. Of thofe, alkaline leys are the chief, being of
extenlive ufe in bleaching, foap-making, glafs-making,
&c.
We therefore made a very ftrong ley of the pureft
vegetable alkali that is ever ufed in the manufactories,
not thinking it neceffary, or even proper, to take it in
1 573 }
S P E
its Hate of utmoft purity, as obtained from cubic nitre Specific
and the like. We took lalt of tartar from the apothe- , Gra^;ty’t
cary, perfedly dry, of which 3983 grains were diffolved v
in 3540 grains of diffilled water} and after agitation for
feveral days, and then Handing to depofit fediment, the
clear ley was decanted. It Avas again agitated } be-
caufe, when of this llrength, it becomes, in a very fhort
time, rarer above and denfer at the bottom. A flafk.
containing 4200 grains of water held 6165 of this ley
when of the temperature 550. Its fpecific gravity Avas
therefore 1.4678, and the 6165 grains of ley contained
3264 grains ol fait. We examined its fpecific gravity
in different Hates of dilution, till we came to a brine
containing 51 grains of fait, and 4x89 grains of Avater,
and the contents of the fialk weighed 4240 grains : its
fpecific gravity Avas therefore 1.0095. In this train of
experiments the progreflion was moH regular and fatif-
faftory } fo that when Ave conHrufted the curve of fpe¬
cific gravities geometrically, none of the points deviated
from a moft regular curve. It Avas confiderably more
incurvated near its commencement than the curve for
lea-falt, indicating a much greater condenfation in the
diluted brines. We think that the following table, con-
H.rufted in the fame manner as that for. common fait,
may be depended on as A'ery exaft.
Weight of
Cub. Fcot
oz.
IOOO
1016
10^1
I045
1085
1071
1084
1098
1112
112 c
1138
1150
1162
bait
cont.
oz.
o
20
40
60
80
100
I 20
I40
l6o
l8o
200
220
240
Weight of
Cub. Foot
oz.
1174
1187
I 200
12X2
1224
1236
I 248
1259
1270
1281
1293
I3°5
Salt
cont
oz.
260
280
300
2 20
340
360
380
400
420
440
460
480
500
Weight of
Cub Foot
1329
*340
l3Sl
1362
I372
1384
*39$
1406
I4I7
1428
t438
X449
1.460
Salt
cont.
}20
540
c6o
580
600
620
640
660
680
700
720
740
760
Weight of
Cub. Foot
I47I
1482
J493
I5°4
15I5
1526
L537
1347
*337
IJ67
I577
1586
Salt
cont.
02.
780
800
820
840
860
880
900
920
940
960
980
1000
We fee the fame augmentation of the denfity of the
ialt in the diluted brines here as in the cafe of common
fait. Ihus a brine, of Avhich the cubic foot weighs
1482 ounces, or Avhich has the fpecific gravity 1.482,
contains 800 ounces of dry alkali and 682 of Avater,
Iherefore, if avc fuppofe the denfity of the water un¬
changed, there remains the bulk of 318 ounces of water
to receive 840 ounces of fait: its denfity is therefore ?
■ _ 318”
~ 2.512 nearly. But in the brine Avhofe Aveight per
foot is only 1016 there are 20 ounces of fait, and there¬
fore 996 of water ; and there is only four ounce-mea-
fores of water, that is, the bulk of four ounces of Avater,
to receive 20 ounces of fait. Its fpecific gravity there-
r . 20
ore is , _ 5, almoH twice as great as in the flrong
brine. Accordingly Mr Achard is difpofed to admit the
ab for pi ion (as it is carelefsly termed) in the cafe of fal
tart. But it is a general (avc think an univerfal) fadt
in the folution of falts. It mud be carefully diflin-
guilhed from the firH contra&ion of bulk Avhich falts
undergo in pafling from a folid to a Huid form. The
contraction now under confideration is analogous to the
contraction of oil of vitriol when diluted Avith Avater }
for oil of vitriol mud be confidered as a very flrong
brine Avhich we cannot dephlegmate by diflillation, and
therefore cannot obtain the dry faline ingredient in a
feparate form, fo as to obferve its folid denfity, and fay
how much it contracts in firfl becoming fluid. The rvay
of conceiving the firfl contraaion in the ad of folution
as a lodging of the particles of the one ingredient on the
interflices of the other, “ qu"1 i/s fe nichent^ en augmentutit
le poids fans afficier le volume de la faumuref as Euler
and Lambert exprefs themfelves, is impoflible here, Avhen
both are fluids. Indeed it is but a flovenly Avay of
thinking