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| Iodine a Reagent for Hydrosulphurie Acid. . ai 123 
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Arr. XUIL.— The employment of Iodine as a reagent for Hydro- 
_ , sulphuric Acid ; by M. Auevonse pu Pasquier. 
TO THE EDITORS OF THE AMERICAN JOURNAL OF SCIENCE. 
Gentlemen,—T nx original of this article was published in the 
March number of the Annales de Chimie et-de Physique, and 
the importance of its being generally known to those who devote 
any of their time or attention to the investigation of our mineral 
waters, many of which are more or less impregnated with hydro- 
sulphuric acid and the alkaline hydrosulphates, has induced me 
to transmit to you, for publication, a translation of such parts as 
explain the method of employing the reagent in question, and 
the conclusions that M. Alphonse has arrived at by his varied ex- 
_ periments, _ ; ' Oras 
The sulphohydrometer that is described, is of easy applica- 
tion, and enables one to obtain very accurate results in a short 
- Space of time, particularly when use is made of a table that I 
have calculated and annexed. ie : 
_ As regards the strength of the tincture of iodine, that is alto-- 
gether optional with the individual who employs it; it being only 
tequisite to have a knowledge of the amount of iodine contained 
ina measured portion of the liquid. I should propose, as most 
‘convenient, that each division on the sulphohydrometer should 
, answer to ;', of a grain of iodine, and a subdivision to ;}5- 
; Yours respectfully, J. Lawrence Surrn, M. D. 
. Paris, Sept. 20, 1840. ee ee 
“To determine the proportion of hydrosulphuric acid, either 
free or in combination in sulphureous waters, is an operation at- 
tended with considerable difficulty, and of which the results are 
far from being certain. All the methods employed to arrive at 
this end, comprising even the process of M..Grotthuz, (the em- 
ployment of ammoniacal nitrate of silver,) adopted by M. An- 
glada, and the generality of the chemists of the present day, pre- 
Sent great difficulties of detail, and are, as has been demonstrated 
in my first memoir, subject to gross errors, particularly when we 
obtain a sulphuret. more. or less impure ; and moreover when the 
quantity of hydrosulphuric acid is very minute they cease to act. 
“In my researches. upon the waters of Allevard, the uncer- 
tainty of these methods, made me desire to discover some process 
more satisfactory, when, employing as a reagent the alcoholic 
