390 M. Liebig on the Formation of Tartaric Acid from Milk-sugar. 
C6 H7 NO# 
nitropetrol-diamine, C!*H"! N3 04'=N?< H? , a basic sub- 
H? 
stance which crystallizes on slowly cooling from an alcoholic 
solution in large orange-coloured prisms. This body forms ery- 
stalline salts with sulphuric and hydrochloric acids. When it 
is treated with iodide of ethyle, it forms a compound in which 
three of hydrogen are replaced by ethyle—triethylnitropetrol- 
C16 H7(NO4) 
diamine, N?< (C4 H®)? 
(C+ H®)H. 
Petrol has the same composition as xylole (Cahours, Church), 
but, judging from the nature of its derivatives, it does not appear 
to be identical with it. 
Liebig gives a detailed description* of the formation of tartaric 
acid by the oxidation of milk-sugar by nitric acid. He discusses 
the mode of occurrence and constitution of tartaric acid, and 
several allied vegetable acids, and mentions an experiment in 
which he tried the action of aldehyde on cyanogen dissolved in 
water in the expectation of effecting the synthesis of malic 
acid. It gave, however, an unexpected result. A flask contain- 
ing about two quarts of water was saturated with cyanogen, 
about an ounce of aldehyde added, and the whole left in a 
cool place. The fluid remained clear and colourless; but gradually 
a mass of white crusts separated at the bottom of the flask,which 
were found to be oxamide. The liquid, saturated for a second 
and third time with cyanogen, yielded fresh quantities of oxa- 
mide. On distilling the liquid some more oxamide separated, 
and it appeared as if the aldehyde had formed a combination 
with oxamide which was decomposed by boiling. The aldehyde 
which distilled over contained some acroleine. The mother-liquor 
from which the oxamide had deposited contained oxalate of 
ammonia. 
The aldehyde in this experiment, either by its mere presence 
or by its cooperation, promotes the combination of cyanogen with 
water, to form, according as it combines with two or four equiva- 
lents of water, oxamide or oxalate of ammonia. The aldehyde 
acts as a sort of ferment; while any other affinity of the cyanogen, 
for the hydrogen or for the oxygen of the water, appears to be 
quite suppressed. . 
* Liebig’s Annalen, January and February 1860. 
