1804.] On the Manufatture and Quality of Chefbire Salt, 
of fea-water by the illuftrious Bergman, 
whofe authority ftands among the very 
higheft as a practical operator. This ex- 
celient chemift afcercained the contents of 
fea-water to be the following, (reducing 
tne meafures from the Swedifh to the 
Englith, for the fake of comparifon) : 
One Englith wine pint of fea-water, 
taken up at the latitude of the Canaries, 
contains ; 
prains. 
Of common falt a 241 
Of muriated magnefia 65% 
Of falphate of lime —- 3 
Of thefe three ingredients, the two lak 
are the earthy tmpurities, from which, if 
the earth were precipitated by a carbon- 
ated alkali, as in the former experiments, 
the 658 grains of muriated magnefia 
would yield 45 grains, and the 8 grains of 
fulphate of lime would yield about 6 
grains of earth—total 51 grains. 
~ Thus we fee that the ab/folute quantity 
of earth precipitable from a pint of 
Chefhire-brine, is nearly the fame as from 
apint of fea-water; but the relative pro- 
portion of this earth to the pure muriate of 
joda, is totally different; fince a given 
bulk of the Chefhire brine contains tull 
ten times as much pure falt as tne fame 
quantity of fea-water. Confequently it 
would be néceflary to evaporate at lcaft ten 
times as much fea-water as Chefhire-brine, 
to obtain a pound of falt ; and, therefore, 
if the impurity of the fource whence falt 
is obtained were to affet the quality of 
the manufactured product, as the author 
of the paper infinuates, it would fullow that 
the bay-falt, which is procured from fea. 
water, ought to contain ten times the im- 
purity of that of Chethire manafatiure, 
which is fo much reprobated. 
_ The following experiments will thew 
how fmall is the proportion of ear:hy- {alt 
‘contained in rock-falr, or in ‘the fale 
which “is procured from the Chethire 
brine-fprings, either natural, or when 
ftreng’hened with rock falt. They will 
convince us, that if this laft be not found 
to prefervé anima! fubttances from putre- 
faction, at leaft equally well with other 
falts, it cannot be owing to the wanr of 
purity inthe falt; but mult be afcribed to 
fome other caufe. ° 
Experiments. —480 Grains of rock-falt 
were diffolved in four ounces of diftlled 
water. i 
1. On addition of carbonate of potafh, 
there was no precipitate. i, 
2. No alteration was produced by this 
folution on blue vegetable juices. 
3. On addition of a few drops of ftinc- 
“A 
445 
ture of galls, a flight purple tinge was 
_given tothe folution; and, after ttanding 
fome hours, there was a brown fedimene 
at the bottom of the pial. 
4. On addition of muriace of barytes, 
-NO precipitate. 
The firft experiment fnews that the 
rock-falt has no muriaie of lime or mu- 
riate of magnefia combined with it, earthy 
falts always met with in fea-water, and 
generally in brine. The fecond, that it 
has no uncombined acid or alkali. The 
third, that :¢ contaivs {ome portion of iron. 
The fourth, that there is no fulphate of 
lime (gypfum) coniained in it. 
Though the prelence of a {mall quan- 
tity of iron gives a brown fh tinge to a 
large quantity of fait, it has never been 
fuipecied to injure the quality of the falt, 
or to leflen is power of reiting putre- 
faction. [he iron here found is a car- 
bonate ; and if the brine be left for a few 
days inthe refervoir, previous to iis being 
drawn into the evaporating-pan, the 
greater part of the acid leaves the iron, 
and the oxyd fubfides to the bottom of ihe 
ciltern. If any ftiil remain united with - 
the acid, when the brine is heated to 100 
é 
‘cegtees of Fahrenheit in the evi porating= 
pan, the acid quits the iron, and the Jatter 
then fubfides. As the oxyd of iron affects 
only the colour, and does not diminifh the 
ufe of the falt, lefs pains is taken to fepa- 
race it.* ig 
Similar experiments made with folu- 
tions of ftoved (or fine-grained), fair, 
and’ wih larg:-grained (fithery) falt, of 
Chefhire manutagture, fuch as are indif- 
criminately expoited or ufed in England, 
fhew, that the portion of ear'hy-falts 
contained in them is much too fmall to 
have any eff:¢t in leflening the value of 
the falt, and much fmaller than is met with 
in [ult of any other manujadture. 
Experiment.—48o0 Grains of ftoved. 
falt (prepared by a boiling-heat) were 
difluived in 4 oz. of diltilled water. 
1, A precipitate was produced by a 
foluiion of carbonate of potafh, which, 
when dried, amounted to 3-grains, and 
was found to confiit of carbonate of lime 
and carbonate of magnefa. 
2. On adding muriate of barytes, there 
was a white precipitate. 
3. No alreration was produced by a 
fimijar folution on blue vegetable juice ; 
* At Walker, in Northumberland, the 
quantity of carbonate of iron contained in 
the brine, is fo great, that itis feparated by 
throwing quicklime into the refervoir 5 and 
the ochre is prepared for fale. Ah 
| but 
