DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 279 
It might appear much simpler to consider the formula of this substance as being 
but half of the above, C n H 8 0 3 , and the lead salt as C n H 8 0 3 + PbO. But it will 
be seen that circumstances connected with the other substances of this series show 
that the equivalent contains the larger formula. A more important objection to which 
the formula just given is exposed, arises also from the constitution of many of the 
bodies to be afterwards described, that the number of equivalents of hydrogen is not 
sixteen but fifteen. The grounds of this supposition shall be hereafter noticed, and 
for comparison I will here insert the result calculated on that idea. 
22 Carbon . . 
. 134*2 
68*06 
15 Hydrogen 
15*0 
7*60 
6 Oxygen . . 
48*0 
24*34 
197*2 
100*00 
The value of the carbon is but slightly altered, but the difference of hydrogen is 
very great ; if the true value for hydrogen be fifteen atoms, then in one case there 
was 0*67 of hydrogen obtained too much. Notwithstanding this some may be inclined 
to adopt this number. 
1 1 . Of Erythrine. 
This substance being the pseudo-erythrine of Heeren, has been very determinately 
characterized by that chemist in his description of its properties. It is but very 
sparingly soluble in cold water ; in boiling water, on the contrary, it dissolves in great 
abundance, and on cooling separates under the form of micaceous plates of consider- 
able lustre. Its fresh solution in water is colourless, but if it be kept for a little time 
exposed to the air, particularly when hot, it rapidly becomes brown, still remaining, 
however, clear and transparent. The erythrine is then wholly, or in great part de- 
composed, and on cooling little or no deposition of crystals occurs. 
Erythrine is very soluble in alcohol and ether ; also in alkaline solutions, from 
which, however, it is precipitated unchanged on the addition of an acid. If its alka- 
line solutions be exposed to the air, they become coloured after a little time, brown 
with potash or soda, but wine-red if the alkali be ammonia. 
At a temperature of about 220° Fahr., erythrine fuses without losing water. 
When further heated it is decomposed, giving the usual products of unazotized or- 
ganic matter, without any portion being volatilized. 
It does not precipitate any neutral metallic solution. If a solution of erythrine in 
ammonia be added to nitrate or acetate of lead, a copious white precipitate falls, 
which contains erythrine, and which was subsequently analysed. 
To determine the composition of erythrine, the following analyses were made. 
A. 0*428 gramme of material gave 0*947 gramme of carbonic acid, and 0*239 
gramme of water. 
B. 0*347 gramme of material gave 0*769 gramme of carbonic acid, and 0*194 of water. 
