WATERS, MINERAL. 
portion of that salt which has been exposed, 
spread on a paper, for a few hours to the 
air, is to be added to the solution of the 
magnesian salt sufficiently concentrated; 
or to a water suspected to contain magne- 
sia, after being very much reduced by eva- 
poration. No precipitate will appear, till 
a solution of phosphate of soda is added, 
when an abundant one will fall down. Let 
this be dried in a temperature not exceed- 
ing too® Fahrenheit. One hundred grains 
of it will indicate nineteen of magnesia, or 
about sixty-four of muriate of magnesia. 
Muriate of Lime. — Muriate of lime is 
principally of use in discovering the pre- 
setice of alkaline carbonates, which, though 
they very rarely occur, have sometimes 
been found in mineral waters. Of all the 
three alkaline carbonates, muriate of lime 
is a sufficient re agent ; for those salts se- 
parate from it a carbonate of lime, soluble, 
with effervescence, in muriatic acid. 
With respect to the discrimination of the 
different alkalies, potash may be detected 
by muriate of platina. Carbonate of ammo- 
nia may be discovered by its smell ; and by 
its precipitating a neutral salt of aiumine, 
while it has no, action apparently on mag-^ 
nesian salts. , 
To estimate the proportion of an alkaline 
carbonate present in any water, saturate 
its base with sulphuric acid, and note the 
weight of real acid which is required. Now 
too grains of real sulphuric acid saturate 
181.48 potash, and 78.32 soda. 
Analysis of Waters by Evaporation . — 
The reader, who may wish for rules for the 
complete and accurate analysis of mineral 
waters, will find in almost every chemical 
work a chapter allotted to this subject. He 
may consult Kirwan’s “ Essay on the Ana- 
lysis of Mineral Waters,” London, 1799. 
Before evaporation, however, the gaseous 
products of the water must be collected, 
which may be done by filling with it a 
large glass bottle, or retort, capable of hold- 
ing about fifty cubic inches, and furnished 
with a ground stopper and bent tube. The 
bottle is to be placed up to its neck in a 
kettle filled with brine, which must be kept 
boiling for an hour or two, renewing, by 
fresh portions of hot water, what is lost by 
evaporation. The disengaged gas is con- 
veyed, by a bent tube, into a graduated 
jar, filled with, and inverted in, mercury, 
where its bulk is to be determined. On the 
first impression of the heat, however, the 
water will be expanded, and portions will 
continue to esc.ape into the graduated jar 
till the water has obtaineil its maximum of 
temperature. This must be suffered to es- 
cape, and its quantity to be deducted from 
that of the water submitted to experiment. 
In determining, with precision, the quan- 
tity of gas, it is necessary to attend to the 
state of the barometer and thermometer. 
The gases most commonly found in mine, 
ral waters, are carbonic acid ; sulphuretted 
hydrogen; nitrogen; oxygen gas; and, in 
the neighbourhood of volcanoes only, sul- 
phureous acid gas. 
To determine the proportion of the gases, 
constituting any mixture obtained from a 
mineral water in the foregoing manner, the 
following experiments may be made. If 
the use of re-agents has not detected the 
presence of sulphuretted hydrogen, and 
there is reason to believe, from the same 
evidence, tliat carbonic acid forms a part of 
the mixture, let a graduated tube be nearly 
filled with it over quicksilver; pass up a 
small portion of solution of potash, and agi- 
tate this in contact with the gas; the 
amount of the diminution will show how 
much carbonic acid has been absorbed ; 
and, if the quantity submitted to experi- 
ment was an aliquot part of the whole gas 
obtained, it is easy to infer the total quan- 
tity present in the water. The unabsorb- 
able residuum consists, most probably, of 
oxygen and azotic gases; and the propor- 
tion of these two is best learned by the use 
of Dr.' Hope’s eudiometer. 
If sulphuretted hydrogen be present, 
along with carbonic acid, the separation of 
these two is a problem of some difficulty. 
Mr. Kirwan recommends, that a graduated 
glass vessel, completely filled with the mix- 
ture, be removed into a vessel containing 
nitrous acid. This instantly condenses the 
sulphuretted hydrogen, but not the car- 
bonic acid gas. It seems to be a more eli- 
gible mode to cdndense the sulphuretted 
hydrogen by oxymuriatic acid gas (obtain- 
ed from muriatic and hyper-oxymuriate of 
potash), adding the latter gas very cau- 
tiously, as long as it produces any condensa- 
tion. Or, perhaps, a better plan of effect- 
ing the separation is the following, recom- 
mended by Mr. Henry : half fill a graduated 
phial with the mixed carbonic acid and sul- 
phuretted hydrogen gases, and expel the 
rest of the water by oxymuriatic aeid gas. 
Let the mouth of the bottle be then closed 
with a well ground stopper, and let the 
