Use of Carbonic Acid in analyzing Mineral Waters. 215 
as long as the gas gives a distinct trace of S H by the tache on 
porcelain as before described ; and then by precipitation to deter- 
mine the quantity of sulphur in the alkaline sulphid of the re- 
maining liquid. 
rom what has been said it is obvious that the only practical 
objection to the process here proposed is the tardiness of tle dis- 
placing action of the hydrogen gas; but considering the acknowl- 
edged imperfection of the methods in use, we think that it may 
be found worthy of adoption. 
Second.—On the use of Carbonic Acid Gas in the analysis of 
mineral waters containing Sulphuretted Hydrogen. 
As might be inferred from its great absorbability by water, car- 
bonic acid acts much more rapidly than hydrogen in separating 
hydrosulphurie acid from that liquid. _ ‘I'o assure ourselves of this 
effect, we made several experiments with natural and artificial 
sulphureous waters, all of which led to the same result. The 
More easy separation and determination than when formed in the 
Usnal way by adding a precipitant to a large mass of the mineral 
ater. In the case of feebly sulphureous waters this method is 
We think greatly superior in accuracy as well as promptness to 
“hy of those in use. By operating on a considerable volume of 
AS carbonic acid is capable of decomposing the sulphids con- 
‘dined in a mineral  eaagena rise to free hydrosulphuric acid, 
