APPENDIX. 127 
variations in the animals employed in the experiments. The cireum- 
stance that theine was found to be more active than caffeine, and to be 
capable of producing effects not produced by caffeine, tends to support 
the view that the theine was impure. It is now well known that tea 
contains other bases than caffeine, the presence of traces of which 
might be sufficient to account for the observed differenc eS. 
During the preparation of the pure aurochlorides for a comparison 
of their properties the authors obtained two new and inter esting 
auric derivatives of caffeine 
When an aqueous solution of caffeine aurochloride is heated, a 
yellow, flocculent precipitate is gradually formed, which is insoluble - 
in alcohol, chloroform, and ether, but dissolves in hydrochloric acid, 
reproducing the aurochloride, The substance dried at 100° forms a 
pale yellow amorphous powder, which melts at 207° (corr.), Analysis 
proved it to be aurochlor caffeine C°H*(AuCl*?)N*O*, a substance 
in which one atom of hydrogen in caffeine is replaced by the group 
(AuCl), It is pointed out that the ready formation of this remarkable 
compound from caffeine aurochloride by the loss of two molecular pro- 
portions of hydrochloric acid—C*H?°N*O2, HCl, AuCl*=2 HCl+- 
C*°H* (AuCl’) N*O*—is better shown by Medicus’s formula for 
caffeine, than by that proposed by Emil Fischer, since in Medicus’s 
formula the CH group which loses hydrogen is represented as con- 
tiguous to the doubly-linked nitrogen atom, to which the auric- 
chloride is attached, 
By the reaction of an alcoholic solution of potassium chloraurate 
(KCl, AuCl*) with a solution of caffeine in chloroform, a salt, 
crystallizing in the dark red needles, was cbtained. This is shown to 
be caffeine potassium aurochloride (C‘H**N*O?, KCl, AuCl*) which 
iffers from caffeine‘nurochloride in containing potassium in the 
place of the hydrogen of hydrochloric acid, This salt melts at 208° 
(corr.). It readily dissolves in alcohol and water, forming yellow 
solutions which appear not to contain the salt itself, but its 
constituents, caffeine and potassium chloraurate. The salt is 
nearly insoluble in ether and chloroform, but prolonged contact with 
these liquids leads to its decomposition into caffeine and potassium 
choloraurate (W.R. Dunstan and W. F. J, Shepheard, from the 
Research Laboratory of the Pharmaceutical Society—The substance 
of @ communication made, to the Chemical Society, December 15th, 
1892. 
