260 
MISCELLANY. 
nitric acid be present, the liquid immediately assumes a rose or even pur- 
ple color, and such is the sensibility of the reagent that one part of nitric 
acid will color in a distinct manner even 24,000 parts of liquid. This color 
is due to deutoxideof nitrogen, which is produced and remains dissolved 
in the excess of the sulphate of iron. 
To detect the existence of nitrogen in a gas, it is to be exploded in an 
eudiometer, along with three or six times its bulk of a mixture of equal parts 
of hydrogen and oxygen ; the instrument is then to be washed with sulphu- 
ric acid, to which some drops of protosulphate of iron has been added, and 
if nitrogen has been present, the small quantity of nitric acid produced by 
the explosion will be sufficient to produce a distinct color in the liquid. 
LPInstitut. 
On the oil of Mint, and upon a new carburet of hydrogen derived therefrom, 
by M. Walter.-OH of mint, pure and crystallized, melts at 34° c. and boils 
at 213,°5. It is composed of 
C 40 . , 1530.40 . . 0.7727 
H 40 . . 250.00 . . 0.1262 
02 . . 200.00 . . 0.1011 
The density of its vapor was found to be 5.62, the formula gives 5.455. 
On adding to this oil small quantities of anhydrous phosphoric acid, until 
there ceases to be any increase of temperature, distilling and then re-distil- 
ling with anhydrous phosphoric acid, we obtain a transparent liquid which 
boils at 163° c, and which I designate by the name of menthene. This 
substance is composed of 
C 40 . . 1530 . . 0.8718 
H36 . . 225 . . 0.1282 
1 found the density of its vapor to be 4.93 to 4.94; calculation gives 
4.835. In evaporating, it becomes brown and slightly altered. 
Acad, des Scien. 
On a new carburet of Hydrogen, by M. Cahore. — On treating the oil of 
potatoes, which is an alcohol, by anhydrous phosphoric acid, and distilling 
several times from this acid, we obtain a liquid, oily, light, of an aromatic 
odor, boiling at about 160°, and composed of 
C2Q .... 0.86 
H 20 .... 0.14 
This is then a true carburet of hydrogen, having the same composition 
as methylene and olefiant gas ; and differing but in the state of condensa- 
tion of its elements. I found the density of its vapor to be 5.06 ; by calcu- 
lation it should be 4. 904, on the supposition that C20 and H 20 represent 
two volumes. Ib. 
A method to prepare the Sulphate of Iron so as to preserve it always at a 
minimum of oxidation, by M. Berthemot. — Having dissolved the sul- 
