I 
DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 309 
When this salt is dried at 180° it retains about 3*5 per cent, of water, which it loses 
at 250°. In this hydrated form, its constitution is probably C 18 H 7 0 16 -}- 5 Pb O + 
3 Aq. 
With oxide of silver the spaniolitmine gives a fine purple lake, which gradually be- 
comes black on exposure to light. It was analysed. 
0*894 of a portion dried at 212°, gave by ignition 0*482 of metallic silver. 
1*762 gramme of the same specimen gave 1*206 of carbonic acid, and 0*271 of water. 
These numbers give the formula C 18 H 7 O ie + 3 Aq O. 
♦ 
18 Carbon . 
. = 109*8 
Theory 
18*53 
Experiment. 
18*92 
7 Hydrogen 
7*0 
1*18 
1-61 
19 Oxygen . 
152*0 
25*64 
25*55 
3 Silver 
324*0 
54*65 
53*92 
592*8 
100*00 
100*00 
If the solution of spaniolitmine in water of ammonia be decomposed by basic ace- 
tate of lead, there is produced a fine azure-blue precipitate, which is not altered by an 
excess of ammonia ; and as it appeared to contain almost exactly the same quantity 
of oxide of lead, in portions prepared at different times, it was looked upon as being 
definite in constitution, and was analysed. 
A. 1*762 gramme of substance dried at 250° in an oil bath, gave 0*520 of oxide of 
lead, and 0*900 of metallic lead, being 85*35 Pb O in 100. 
B. 2*161 gramme of another portion, dried also at 250° in an oil bath with Liebig’s 
apparatus, gave 1159 of metallic lead, and 0*558 of oxide of lead, equivalent to 84*31 
Pb O in 100. 
C. 3*558 gramme of the same specimen gave 0*152 of water, and 0*846 of carbonic 
acid. 
The formula which results is C 18 H 7 0 16 -j- 12 Pb O. 
Theory. Experiment. 
18 Carbon . . . 
109*8 
6*93 
6*58 
7 Hydrogen . . 
7*0 
0*44 
0*43 
16 Oxygen . . . 
128*0 
8*08 
8*68 
12 Oxide of lead . 
1339*2 
84*55 
84*31 
1584*0 
100*00 
100*00 
If this substance be dried at the temperature of 150° it retains five per cent, of 
water, which it loses completely between 212° and 250°. This quantity is almost ex- 
actly nine equivalents, and hence probably the hydrated salt is C 18 H 7 0 16 -f- 12 Pb O 
+ 9 Aq, or C 18 H 7 0 16 + 3 Pb O + 9 (Pb O Aq). 
The result of these different analyses justify, in my opinion, fully the formula which 
I have adopted for their expression. It might perhaps be urged that in the analysis 
of the^ilver salt, there was obtained too much carbon by 0*39 per cent., and that this 
