PEOFESSOE B. C. BEODIE ON THE ATOMIC WEIGHT OF GEAPHITE. 255 
These results correspond to the following per-centage 
1. 2. 
composition : — 
3 . 
4 . 
Carbon . 
. . 80*19 
79*64 
79*40 
79*27 
Hydrogen . 
. . 0*52 
0*57 
0*55 
0*60 
Oxygen . . . 
. . 19*29 
100*00 
19*79 
100*00 
20*05 
100*00 
20*13 
100*00 
When this substance was carefully examined under the microscope, traces of trans- 
parent crystals could still be perceived, similar in appearance to the original substance. 
To preclude the possibihty of an error from the imperfect decomposition of the substance, 
the following experiments were made, in which the substance was submitted in the 
naphtha to a prolonged action of heat, for fourteen hours. 
Expt. IV. 3*9185 grms. of substance gave 2*577 grms. of residue. 
Expt. V. 17*175 grms. of substance gave 11*2965 grms. of residue. 
In Experiment IV. the temperature was raised to 240° C., in Experiment V. to 220° C. 
These results correspond to a loss on 100 parts of the substance~in Experiment IV. of 
65*76, in Experiment V. of 65*77 parts. 
The analyses of these substances gave the following result : 
Substance taken. Carbonic acid formed. Water formed. 
1. Expt. IV. . . . 0*377 1*1126 0*0210 
2. The same . . . 0*4766 1*4068 0*0255 
3. Expt. V. . . . 0*3835 1*1327 0*022 
Ihese analyses give the following per-centage composition of the substance:— 
1 - 2 . 3 . 
Carbon 80*48 80*50 80*56 
Hydrogen .... 0*62 0*59 0*63 
Oxygen 18*90 18*91 18*81 
100*00 100*00 100*00 
In this substance, placed under the microscope, no traces of the transparent plates of 
the original body could any longer be perceived. The result, therefore, of heating the 
substance for the ten additional hours had been to increase the per-centage of carbon in 
the residue from about 0*5 to 1 per cent. It is evident that the decomposition is arrested 
at about this point ; and if we take the mean, as may reasonably be done, of three 
analyses of the first and the three of the second series of experiments, as representing the 
constitution of the body, we have the following as its per-centage composition: — 
Carbon 80*13 
Hydrogen .... 0*58 
Oxygen 19*29 
2 M 2 
100*00 
