13 
dilute hydrochloric acid, and washing the precipitate by 
Bunsen’s filter pump, but also this product contains hydro- 
chloric acid, which was only given off above 110°. 
By spontaneous evaporation of an alcoholic solution, 
aurine is obtained in dull red crystals, with a green metallic 
lustre. Dried at 110° this body contains no alcohol, but 
still retains a large quantity of water, which only escapes 
between 140° — 180°, the crystals not changing their appear- 
ance at all, and they may be heated up to 200° without any 
further alteration, which fact does not agree with Fresenius’ 
observation, that aurine crystallised from alcohol or acetic 
acid melts at 156°. The analysis of this body, dried at 200°, 
which we believe to be pure aurine, gave numbers closely 
agreeing with the formula C 20 H 14 O 3 and the mode of its 
formation may, if this formula is correct, be expressed by 
the equation. 
3C 6 h g o + c 2 o 2 = cys, a + 2HA 
The substance dried at 110° lost at 180° o’ 4^ of water 
corresponding to the formula C 2d H u 0 3 -f H 2 0.* 
Caro and Wanklyn obtained by the action of nitrous acid 
on rosaniline a body, which they believe to be identical 
with aurine, and to which they assign, from the mode of 
formation, the composition C 20 H 16 O 3 >t differing from our 
formula only by two atoms of hydrogen. 
Nascent hydrogen converts aurine into colourless leuco- 
a urine C 20 H 18 O 3 . This reduction may be effected by heating 
it in an alkaline solution with zinc dust, but at the same 
time a dark resinous body is formed, from which the leuco- 
aurine cannot be easily freed. Better results are obtained 
by acting with zinc dust on a solution of aurine in strong 
acetic acid. Leuco-aurine crystallises from acetic acid or 
alcohol in compact colourless prisms. 
A body resembling leuco-aurine is contained in crude 
aurine ; we have not as yet obtained it in a pure state. It 
*Fresenius analysed aurine which was crystallized from alcohol and dried at 
100°. His numbers agree exactly with the formula C 3o Ilj 4 0 3 -f-2iH 2 0. 
■(■Proceed. Koy. Soc. xr., 210. 
