306 
DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 
almost identical with the former results, and indicating 1 either the formula to be 
C 36 H 21 N 2 0 21 , or that this substance retains half an equivalent of water very power- 
fully, and the formula becomes C 18 H 10 N O 10 + ^ Aq, by which the numbers are 
given : 
18 Carbon . . . . . 
10"5 Hydrogen . . . 
10'5 Oxygen and nitrogen 
50-27' 
4-81 
uoo-oo 
44-92 J 
109-81 
10-5 
98-1 
^218-4 
I was anxious to examine the compound of this body with ammonia, but found that 
it gave results much less definite than those obtained with the erythrolitmine and 
the orceine. If the blue ammoniacal liquor be evaporated to dryness, the ammonia is 
expelled for the most part along with the last portion of water, but the quantity 
which remains behind is not constant. The absorption of dry ammonia was found 
also to be too irregular to be made the basis of numerical results. 
The ammoniacal solution of azolitmine gives with metallic solutions precipitates 
which are either purple or blue, according to the proportion of metallic oxide which 
they contain. Using the precautions already so often described, the combinations of 
azolitmine with metallic oxides are produced, containing the smallest possible propor- 
tion of base, and of a fine purple. In this way the specimens were prepared, the ana- 
lyses of which will now be detailed. 
The azolitmate of lead , although of a beautiful purple when freshly prepared, loses 
that tint when dried with Liebig’s apparatus in an oil bath, and becomes blue. Of a 
specimen dried at 250° Fahr. 1-226 gramme gave 0-512 of oxide of lead, and 0"218 
of metallic lead. 
1-188 gramme of the same substance gave 0-832 of carbonic acid, and 0-220 of water. 
From this results the formula C 18 H 10 N O 10 -f- 3 Pb O, giving 
Theory. 
Experiment. 
18 Carbon . . 
. . = 109-8 
20-01 
19-35 
10 Hydrogen 
. . = 10-0 
1-82 
2-00 
1 Nitrogen . 
. . = 14*1-1 
17-15 
19-27 
10 Oxygen . . 
. . = 80-0 J 
3 Oxide of lead 
. . . = 334-8 
61-02 
59-38 
548-7 
100-00 
100-00 
The salt or lake formed with protoxide of tin in the cold is of a beautiful purple 
colour. It gave the following result. 
0- 611 gramme of material gave 0‘466 of carbonic acid, and 0 - 156 of water. 
1- 328 of material gave, by ignition until all organic matter was burned out, then 
moistening with nitric acid and subsequent ignition a second time, 0777 of oxide of 
tin (peroxide) quite white. 
