DU. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 307 
The formula C 18 H 10 N O 10 + 4 Sn O + 2 Aq, gives 
Theory. 
Experiment. 
18 Carbon . 
. . 109-8 
22-01 
21-10 
12 Hydrogen 
. . 12-0 
2-41 
2-84 
1 Nitrogen . 
. . 14-1 
X 28-48 
30-07 
1 6 Oxygen . 
. . 128-0 
j 
4 Tin. . . 
. . 235-6 
47-10 
45-99 
499-5 
100-00 
100-00 
If a temperature be applied to this salt sufficiently high to expel the water, it be- 
comes partly decomposed, and was hence analysed only in this hydrated condition. 
If when in this state it is boiled with water it becomes completely decolorized, and 
the tin is changed into the form of peroxide, a grayish white compound is produced, 
which rapidly absorbs oxygen, and generates, thereby, a red compound of regenerated 
azolitmine with peroxide of tin. The exact nature of the reaction to which this effect 
is due, will be examined in detail hereafter. 
This azolitmine, which is the only constituent of litmus containing azote, appears 
by the analytical results just given to be connected in a most simple and remarkable 
manner with the principles of archil, alphaorceine and betaorceine. In fact, the pro- 
portion of carbon, of hydrogen, and of azote being the same in these bodies, they 
differ only in the quantity of oxygen they contain, their formulae being 
Alphaorceine . . . C 18 H 10 N 0 5 . 
Betaorceine .... C 18 H 10 N O s . 
Azolitmine .... C 18 II 10 N O 10 . 
As in this portion of the paper I wish to confine myself to experimental results, I 
shall not enter now into any consideration of their theoretical nature, further than 
to notice, that as in the series of erythrolein and erythrolitmine, although these bo- 
dies are simply produced by the continued action of oxygen, yet when once formed 
they cannot be looked upon as oxides of the same compound radical, but are sub- 
stances totally independent of each other. \ 
IV. Of Spaniolitmine. 
In the majority of cases, the salt of lead prepared from the solution of litmus in 
water contains only azolitmine, but in some, I recognized the presence of the substance 
noticed under the name of spaniolitmine in the description of the analysis of litmus, 
and which is distinguished from azolitmine by not containing nitrogen. The exist- 
ence of this substance rendered useless a great mass of results which I had obtained 
in the commencement of my investigations ; the substances employed having been 
mixtures in variable proportions of the two bodies, and having consequently given 
analytical expressions for the soluble colouring matter of litmus, different in each ex- 
periment. The source of this was at last traced to the presence of spaniolitmine, 
which, when once mixed with azolitmine, cannot be separated from it by any method 
2 r 2 
