MISCELLANY. 
83 
and the author has made his new method of analysis very convenient by 
means of an instrument which he has named the sulphydrometre. This 
instrument is a graduated tube, filled with the tincture of iodine, one of 
the ends is closed with a stopper, while the other is slender, and termi- 
nates by a capillary orifice, which permits the tincture of iodine to escape 
in drops from the time that the stopper is removed. To use the sulphy- 
drometre, pour into a porcelain capsule a fixed quantity of sulphurous wa- 
ter to be analysed, add a few drops of the solution of very clear starch, 
then add the tincture of iodine gradually, taking care to assist the reac- 
tion by stirring the mixture with a glass rod. As long as any traces of 
the sulphydric acid remain, the iodine will carry off the hydrogen, by pre- 
cipitating the sulphur, and disappear immediately without colouring the 
starch, but as soon as the saturation is completed the least trace of the free 
iodine is sufficient to give a beautiful blue colour to the solution. 
Then count how many degrees the tincture has disappeared in the sul- 
phydrometre — of which each degree is equal to one centigramme of iodine, 
and each tenth of a degree, one milligramme. The quantity of iodine re- 
quisite to saturate a litre full of sulphurous water, being given, it is very 
easy to find how much sulphydric acid this litre of water contained, by 
determining the equivalent of the iodine in hydrogen. The volume of 
this hydrogen being known, we have that of the sulphydric acid, which 
is exactly the same. To render the use of this instrument more conve- 
nient, the author has made a table which indicates in weight and in vo- 
lume the quantity of sulphydric acid, represented by 1, 2, 3, &c. 100 cen- 
tigrammes, 1, 2, 3, &c. 100 milligrammes. 
This method of analysis, independently of giving results of a rigorous 
exactitude, has the advantage of being so quickly performed that fifteen 
or twenty experiments can be made in less than an hour. It is also so 
extremely simple, that it does not require a chemist to determine the pro- 
portion of sulphydric acid contained in a mineral water ; any intelligent 
person can each day observe the precise variations in the strength of the 
sulphurous waters, either by atmospheric influence or the mixture of wa- 
ter. Among other advantages this method possesses, M. Dupasqnier 
shows its sensibility, which is so great that it indicates the precise quan- 
tities of sulphydric acid in those waters upon which other reagents pro- 
duce no effect, while they evidently show a sulphurous character. The 
tincture of iodine really can (he assures us) disclose in a decided manner 
a drop of a concentrated solution of an alkaline sulphydrate, poured into a 
hecto litre of water, while the known reagents become powerless if they 
are merely poured into ten litres of water. 
Preparation and Employment of the Sesqui-Ioduret of Iron.— M. Ober- 
doerffer, a pharmaceutist of Hamburgh, gives the following formula for 
