MR. JOHNSTON ON THE CONSTITUTION OF THE RESINS. 
379 
the experimental constitution is presented in the results of analyses 17 and 18, 
p. 376. 
2. The precipitate which falls on the addition of ammonia. 
A. Of this salt, washed and dried for several days at 200° Fahr., 
7' 137 grs. left 2 - 957 of oxide of lead, or 41‘41 per cent. 
12*08 grs. gave C = 18*01, and H = 4*813 grs., or per cent., 
(25). 
Carbon 40*95 
Hydrogen 4*42 
Oxygen 13*22 
Oxide of lead 41*41 
40 atoms. 
26*45 atoms. 
9*88 atoms. 
2*21 atoms. 
100 
The resin alone gives 
Carbon 69*88 
Hydrogen 7'54 
Oxygen 22*58 
100 
The oxide of lead is evidently not in atomic proportion, being thrown down pro- 
bably in excess by the ammonia. But the resin indicates the formula C 40 H 26 O 10 , 
which differs from any we have yet met with, in the analysis of the resin in its various 
states, as above-detailed, though other analyses, which I have not thought it necessary 
to insert, have given me results which would lead to a similar formula. 
B. Of the salt last analysed, I decomposed a portion by boiling it with dilute 
muriatic acid, washed the resin well with water, dissolved it in alcohol, and dried it 
by a gentle heat, when 
8*97 grs. gave C = 22*79, and H = 6*1 36 grs. 
Compared with analysis A. and with the formula C 40 H 26 O 10 . 
This result gives per cent. 
A (25). 
B (26). 
c 40 Hog O 10 gives 
Carbon 
69*88 
70*25 
69*77 
Hydrogen 7'54 
7*60 
7*40 
Oxygen 
22*58 
22*15 
22*83 
100 
100 
100 
If implicit reliance could be placed on these analyses of the salts of lead, obtained 
directly and by the aid of ammonia, we should conclude that, by the action of oxide 
of lead, the resin of benzoin was separated into two resins represented respectively 
by C 40 H 22 0 9 , and C 40 H 26 O 10 . I am unwilling, however, myself to place implicit 
reliance upon them, knowing now how easily the resin undergoes decomposition by 
slight elevations of temperature ; a fact of which I was not so well aware when these 
3 c 2 
