PEOFESSOE B. C. BEODIE ON THE ATOMIC WEIOHT OF GEAPHITE. 253 
The mean of these analyses (omitting the hydrogen of the first analysis, which is 
evidently faulty) is — 
Carbon . . . 60’74 
Hydrogen . . 1*85 
Oxygen . . . 37‘41 
100-00 
A correction has yet to be made in these numbers. The graphite from which the 
substance is prepared leaves on combustion a slight ash, and during the prolonged 
treatment of the substance a further portion of incombustible matter is introduced, pro- 
bably from the glass of the vessels in which the operations were conducted, which, as I 
have ascertained, may be estimated at 0-5 per cent. When this correction is made, we 
have for the per-centage constitution of the substance — 
Carbon . . . 61-04 
Hydrogen . . 1-85 
Oxygen 
• 
37-11 
100-00 
The formula Cn H 4 O 5 corresponds to 
this result. It requires — 
Cu. . . 
132 
61-11 
H 4 . . . 
4 
1-85 
O 3 . . . 
80 
37-04 
216 
100-00 
This substance has the following properties. It is insoluble in water containing acids 
or salts, but is very slightly soluble in pure water. The crystals, placed upon litmus 
paper, have a feeble acid reaction. It combines with alkalies. When agitated with 
dilute ammonia, it is converted into a transparent jelly, but is not dissolved. On the 
addition of acids it is separated unaltered from this combination in the form of a gela- 
tinous mass resembling silica, which, dried under the air-pump, appears as a slightly 
yellow and spongy body of the same weight as the substance originally treated with 
ammonia. The crystals treated with deoxidizing agents are readily decomposed. When 
a solution of sulphide of ammonium or of potassium is poured upon the dry substance, 
a crackling sound is heard, and a body is ultimately formed possessing the metallic 
lustre and general appearance of graphite itself. Changes similar in appearance take 
place on boiling the substance with an acid solution of protochloride of copper and of 
protochloride of tin. The substances formed in these processes admit of no process of 
purification, and I have not been able to procure them in a state of purity. 
This body belongs very distinctly to the class of acids, but from the insolubility of its 
salts and the facility with which they are decomposed, I have not been able to procure 
them pure. The following determinations, however, indicate it to be bibasic. A por- 
tion of the moist substance sliaken up with baryta-water, washed out, and dried at 
100°, gave a compound containing 21-19 per cent, of barium. The same substance 
suspended in water, and decomposed by a current of carbonic acid, gave a substance 
MDCGCLIX. 2 M 
