302 DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
The second quantity of substance was dried at 250° in order to determine whether 
the twenty-third atom of hydrogen arose from accidentally-present water. It is 
evident, consequently, that the true formula of the erythrolitmine is C 26 H 22 0 12 -j- Aq. 
When the substance has been dried below 212°, it retains, though loosely, another 
equivalent of water, which corresponds to almost exactly three per cent. It is then 
^26 -^22 ^12 “1“ ^ Aq. 
If dry ammonia be passed over erythrolitmine, it is absorbed with the production 
of considerable heat, and if the substance containing 2 Aq be employed, the second 
equivalent of water is expelled. The resulting mass is deep blue. When this mass 
is heated to 212°, it loses the blue colour and a portion of ammonia is expelled, a 
dark reddish purple mass remaining, from which, however, all ammonia cannot be 
expelled. The action is therefore the same with the dry gas as with ammonia dis- 
solved in water. 
This description is substantiated by the following experiments. 
0‘709 of the bihydrated substance, C 26 0 14 , was exposed to a stream of dry am- 
monia until all the water, which at first separated, had been removed by the excess 
of gas, and the substance had become quite dry and cold. It then weighed 0729. 
It was then heated in a current of air to 250° Fahr. until it ceased to lose weight, 
when it weighed 0-687 gramme. Theory indicates the following result. 
^26 ^22 ^12 — 276*6 
Substance 
= 276-6 
Substance 
= 2766 
2 H O = 18-0 
give H O 
= 9-0 
, N H 3 
and then ■— 2 
= 8-5 
nh 3 
= 17-1 
302*7 
294-6 
285-1 
Now 
709 
: 729 
: : 294-6 
: 302-8 
and 
709 
: 687 
: : 294-6 
: 285-5 
If the erythrolitmine had given off all ammonia but retained an equivalent of 
water, the numerical result would have been the same, but the properties of the 
purple-brown substance show that it is a definite compound. It is quite insoluble in 
spirit, and when treated by a dilute acid, immediately assumes the bright red colour 
of pure erythrolitmine. In order further to test its constitution it was analysed. 
0-347 gramme of substance gave 0-691 of carbonic acid, and 0"265 of water. 
N H 
Hence the formula C 26 H 22 C 12 -\ ^ , which gives 
Theory. 
26 Carbon = 158-6 55’63 
Experiment. 
55-07 
23'5 Hydrogen = 23*5 8’24 
8-48 
12 Oxygen = 96-01 
i Nitrogen = 7*0 J 
36-45 
285-1 100-00 
100-00 
