250 PEOrESSOE B. C. BEODIE ON THE ATOMIC WEIOHT OE GEAPHITE. 
with which carbon in the form of graphite enters into combmation. ^ ith this end I 
examined its reactions. _ . , rViPmiral 
The first experiment in which I sncceeded in ehcitmg a difference m the chemical 
reac“f the different forms of carbon, was, in the case of the achon npon them of 
a mixture of concentrated nitric and sulphuric acids. When finely-dinded ^ 
form of lampblack, or charcoal from the decomposition of sugj, is h^ted ^ 
ture of 1 of nitric and 4 of sulphuric acids, the carbon is rapidly o«*zed and a 
substance is formed, soluble in the concentrated acid, but precipitated on the addition 
I " his substance is insoluble in acids and saline solutions, but is soluble m pure 
water and in alkalies. It is accompanied with other products ^ 
cation difficult. When the graphite of Ceylon is treated in a si^ai the 
is veiT different : the graphite becomes of a beautiful pui-ple coloiu, and falls to piece 
in thJfiuid. The substance, after the acid has been washed from it by watei, has muc 
the appearance of the graphite itself, but is darker in coloui'. It was found on analysis 
to contain the elements of sulphuric acid combined with oxygen, with hydiogen m 
with a large amount of carbon. My efforts to procure this substance of a 
position have been unavaiUng; it is insoluble in all reagents ; it ® ° J; 
Long solution of potash, without separation of sulphuric acid, and with slight, it any, 
alteration of weight ; when heated it undergoes a remarkable change ; gases me gii en 
ta ^interior o/the substance, which swells up in a most singular manner and is retoed 
to the minutest state of division. The residue consists of caibon, w ic as e app 
ance and the structure of the lamellar graphite. A similar oxidation takes place w 
the nitric acid in the above experiment is replaced by other oxidizing agents, such a 
bichromate of potash and chlorate of potash. These experiments estabhshed one point 
of importance, the existence of a peculiar compound of carbon in the form 
The dlcovery of this substance led me to tmn my attention to the oxidation of giaph . 
I found that graphite, when heated with a mixture of nitric acid and cltiorate of potas n 
increased in weight, and that the substance formed was, on the “^little hi 
integrated with evolution of gas. The disintegrated substance differed but 1 ttle u 
appearance from the original graphite. The analysis of the body resulting “0 0 h 
preparations, and with a difference in the time of oxidation, gave no ^ 
These difficulties led me to further experiments. I found that nlien the subs ance 
by the treatment of the graphite with the oxidizing mixture was washed free from the 
salts produced in the reaction, and dried at 100“ and agam oxidized, it gradually lindei- 
went a change in appearance, until, after the fourth or fifth repetition of the process, 
the whole of the graphite was converted into a substance of a light yellow colour, coi 
sisting of minute transparent and brilliant plates. Analysis showed that tins change 
was attended with a gradual alteration of the constitution of the substance, u • ^ a . 
tinally, a time arrived when treatments ivith the oxidizing mixture produced no hut 
change. It is remarkable that this result cannot be produced by one prolonged tiea - 
ment; before the oxidation can proceed, the original conditions must be restored. 
