307 
The material used in the gt ogee consisted of wood (in 
a cases Pine), charred either by s es sas acid with heat, 
y heat alone, and in both cases some lation was intro- 
an ge 
0 experiments pieces of wood, which had been previously 
boiled i in dilute sulphuric acid, were heated gradually to 160° 
and 200° C. respectively. The product in both cases was similar 
in appearance to ordinary ape ae but was found to be soluble 
in the nitric acid re-agent.* rther, the substance obtained 
same way as the charr 
Other experiments faites, the use of sulphuric acid) Bases 
almost as soon as the wood haces quite ‘black, or was continued 
longer. In the latter case a typical charcoal was obtained, in- 
soluble in the nitric re-agent, while less heating gave a pro- 
duct soluble in this re-agent, and probably corresponding to 
a low-temperature charcoal. _Among the specimens obtained, 
those soluble in the nitric re-agent were either partially soluble 
in eau de Javelle, or were insoluble, according to the duration 
of the honed used to produce their carbonisation 
The foregoing data show that wood can be charred so as to 
give a product which differs from typical charcoal in its be- 
havisué towards oxidising agents. Moreover, a series of degrees 
of resistance to these re-agents can be obtained, and evidently 
bears a relation to the severity of the charring ess. 
t Pitta to be seen whether all “‘charcoal’’ produced at 
* In some cases the product was treated with ammonia and soaked in 
water, to remove the remaining sulphuric acid, before being tested with the 
two re-agents. 
t Treatment with dilute sulphuric acid and heat owes its effect primarily 
to the concentration of the acid by the loss nd —— but the action of the 
acid is apparently enhanced by heat at certain temperatures. 
