The potash, free ammonia, and uric acid of urine, will interfere 
slightly with the accuracy of this. result, but even this cause of error 
can be avoided, by first adding to another weighed portion of the urine, 
some chloride of platinum with three volumes. of aleohol and one of 
ether; which will give the double chloride of the potash and free ammo- 
nia contained in the urine, that can be subtracted fram what was given 
by the reaction of sulphuric acid. The error arising from: the uric acid 
is seldom more than zobao 3 and this acid may. be separated from the 
urine prior to adding the sulphuric acid, by treating the three drachms 
of urine with thirty drops of muriatic acid, allowing it to stand. for 
twenty-four hours and filtering. J. Lawrence Sirs... 
3. Determination of the amount of Ammonia contained in the At- 
mosphere ; by A. GraEcER, (Archiv. der Pharm.,xliv, p. 35, and Chem. 
Gazet., Jan. 1846, p. 34.)—The method employed by the author, was 
to pass the atmosphere through muriatic acid contained in a convenient 
vessel. After thirty-six cubic feet of air had been made to pass 
through slowly, the acid liquid was evaporated to dryness in a small 
platinum crucible placed in a water bath, chloride of platinum being 
. previously added. The residue was treated with alcohol and ether, 
and the insoluble portion collected and weighed. In the above experi- 
ment 0-006 grm. of ammonio-chloride of platinum were obtained, and 
this was found on calculation to correspond to 2 millionth of carbonate 
of ammonia in the atmosphere., The experiment has been performed 
in both dry and wet weather with very nearly the same result. J. L. 8. 
4, Test for Ruthenium; by M. Cuavs, (Chemist, Jan. 1, 1846-7.) 
—The best means of ascertaining the presence of Ruthenium in the 
ore of platinum, is the following :—Melt it with an excess of nitre in a 
small platinum spoon, exposing it to a strong heat until the mass no 
‘longer swells, but becomes perfectly liquid; then allow it to cool and 
dissolve it in a small quantity of distilled water. A few drops of nitric 
acid produce in the orange colored solution, a black precipitate, cou- 
sisting of ruthenium and potash. If we add hydrochloric acid to the 
liquid in which the precipitate is found, and heat it in a porcelain cap- 
sule, the oxide is dissolved, and by concentration assumes a beautiful 
orange color, Finally, if we cause sulphuretted hydrogen to pass 
through the solution until it has become almost black, and then filter it ; 
a liquid of a beautiful sky-blue color will pass through. L. 8. 
5. Iodine used to distinguish between the Arsenical Antimonial 
taches formed by Marsh’s Apparatus; by M.. Lassalcne, (Comptes 
Rendus, Dec. 1845, p. 1324.)—The taches formed by Marsh’s appara- 
tus are exposed. to vapor of iodine, when, if they be arsenical, they be- 
come of a pale yellowish brown color, which changes to a lemon yellow, 
and subsequently disappears by exposure to air or to a gentle heat. 
