244 
Natural graphite, . . 2’50 | Pelouze and 
G-as carbon graphite, . . 2 3 5 Graham. 
Mean sp. gr., . 2" 29 
It would have been interesting to have added to this list a deter- 
mination of the specific gravity of Brodies’ purified Ceylon graphite ; 
but its minute division causes the air to adhere to it so tenaciously, 
that I have failed in getting any correct determinations of its density. 
3. Charcoal. 
There are comparatively few determinations of the specific gravity 
of pure charcoal. It is in fact not so easy to obtain this substance. A 
specimen of charcoal from pure sugar, repeatedly calcined, and treated 
with chlorine to remove the last traces of hydrogen, and again cal- 
cined, gave me the sp. gr. 1*80 ; but bubbles of air still adhered to 
it, although it was kept for several hours under a good air-pump. 
The following determinations are those recorded : — 
Pure lamp-black, 
1-78 
Baudrimont. 2 
Fibrous gas coke, 
1-76 
Colquhoun. 3 
Compact gas carbon, 
2-08 
Baudrimont. 4 
Powdered coke (mean), 
1-80 
Begnault. 5 
Charcoal from alcohol, 
2-10 
Scholtz. 6 
Charcoal from sugar, 
1-80 
Playfair. 7 
Pure charcoal, without pores, 
1*84 
Griffith. 6 
Mean sp. gr., 
1-88 
From the preceding data we 
take the 
mean specific gr 
e three varieties of carbon to be 
as follows 
: — 
1 Traite de Chimie, vol. v. p. 518. 
2 Baudrimont, Traite de Chimie, vol. i. p. 511. 
3 Colquhoun’s Annals of Philosophy [2], vol. xii. p. 1. 
4 Baudrimont, Traite de Chimie, vol. i. p. 514. 
5 JFtegnau.lt, Traite de Chimie, vol. i. p. 369. 
6 Bottger Specifiche Gewicht. 
7 Experiment recorded above. 
