Use of Hydrogen Gas in analyzing Mineral Waters. 213 
Art. XX VI.—On the use of Hydrogen Gas and Carbonic Acid 
Gas, to displace Sulphuretted Hydrogen in the analysis of 
Mineral Waters, &c.; by Prof. W. B. Rogers and Prof. R. 
E. Rogers. 
First.—On the use of Hydrogen Gas in the analysis of Sul- 
phureous Waters. 
One of the most difficult points in the analysis of mineral wa- 
ters is the determination of the sulphur which is contained in 
many of them in the two conditions of Sulphuretted Hydrogen, 
and a sulphid, either of an alkaline metal or of magnesium or 
calcium. No satisfactory process has we believe yet been de- 
vised for this purpose. It is easy enough by the nitrate of silver 
orchlorid of copper to determine the total quantity of sulphur 
present in these compounds; but iu the subsequent process of 
boiling the liquid preparatory to the precipitation of the sulphur 
of the sulphids, while we expel the free Hydrosulphuric acid, 
We at the same time decompose the sulphid of magnesium or 
calcium which may be present, even. when the process is conduc- 
ed out of coutact with the air, as in an atmosphere of hydrogen 
gas; and if we boil the liquid in the air or even expose it for 
some time to the atmosphere at common temperatures, the sul- 
Phids of sodium and potassium as well as of magnesium = 
“4 
n. 
the hydrogen used for this purpose, before reaching the vessel 
Which contains the mineral water, is conducted through a solu- 
— of potassa in order to remove any hydrosulphuric or carbonic 
*eid it may contain. Thence it is made to pass into a second 
