MISCELLANY. 
263 
analogous to that observed by Messrs. Austin and Chevalier, during the 
oxidation of iron under similar circumstances. 
I procured several specimens of this salt; all the crystals contained 
more or less oxide of iron. Pulverized in a glass mortar, and mixed with 
an excess of caustic potassa, with the addition of a little water, they 
all gave off ammonia, rarely appreciable by the smell, but rendered very 
apparent by the presence of nitric acid that did not fume. Am- 
monia continued thus to be evolved until nearly all the proto-oxide 
was peroxidized, as was ascertained by occasionally renewing the 
surface with a pestle. To convince myself that the white vapours, 
observed in this case, were owing to the presence of ammonia, \ treated 
four hundred grammes of sulphate in a close apparatus, to which was 
attached a small bottle containing water acidulated with chlorohydric 
acid. The reaction being completed, the liquid was evaporated; 1 obtained 
a notable quantity of a salt which, mixed with potassa, evolved a strong 
ammoniacal odour. Other specimens of protosulphate, recently prepared , 
in well formed crystals, and very clear, containing no oxide of iron, were 
treated in the same manner. They did not immediately give off ammonia, 
but only some watery vapour, produced by the elevation of temperature 
of the mixture ; as soon, however, as the surface became oxidized, ammo- 
niacal vapours were evolved and continued to be so, as in the other speci- 
mens. 
We may conclude from these experiments that ammonia is produced 
by the oxidation of protosulphate of iron exposed to the air, and also 
when this salt is decomposed by an alkali, being evolved as long as the 
oxidation continues. Journ, de Pharm, 
Essential Oil of Potatoes. By M. Augustus Cahours, (L'Institut, No. 
199.) — According to Dumas, the essential oil of potatoes is represented 
by the formula, C^o II24 O^. M. Cahours infers that this oil is a com- 
pound analogous to alcohol and spirit of wood, in consisting of a peculiar 
compound of carbon and hydrogen for its base, (C^o H^*^,) united to two 
atoms of water. He cites the following experiments by himself as proof 
of the correctness of this view. 
The oil treated with sulphuric acid, and subjected to a mild heat, yield- 
ed an acid containing the same carburetted hydrogen for its base. This 
acid formed with bases soluble compounds, whose analogy with sulpho- 
vinates is incontestable. The salt of baryta, for example, contained 
S03 Ba 0-l-SO^ C20 H20, O^. If the oil is put in contact with iodine 
and phosphorus, an ethereal substance is disengaged, giving off a slightly 
alliaceous odour, which is similar in composition to hydriodic ether* 
With nitric acid and chlorine, it afforded products of analogous constitu- 
tion. — Amer. Journ. of Science and Arts, 
Silex. — IM.Turpin has submitted the silex sent from Berlin by M. Ehren- 
