70 Mr . Davy's Lecture on some new analytical Researches 
produce very nearly the same quantities of carbonic acid, and 
absorb very nearly the same quantities of oxygene in com- 
bustion. 
Hence it is evident, that they must consist principally of the 
same kind of elementary matter ; but minute researches upon 
their chemical relations, when examined by new analytical 
methods will, I am inclined to believe, shew that the great 
difference in their physical properties does not merely depend 
upon the differences of the mechanical arrangement of their 
parts, but likewise upon differences in their intimate chemical 
nature. 
I endeavoured to discover, whether any elastic matter could 
be obtained from plumbago very intensely ignited by the 
Voltaic battery in a Torricellian vacuum : but though the 
highest power of the battery of five hundred was employed, 
and though the heat was such, as in another experiment in- 
stantly melted platina wire of ^-th of an inch in diameter, 
yet no appearance of change took place upon the plumbago. 
Its characters remained wholly unaltered, and no permanent 
elastic fluid was formed. 
I heated one grain of plumbago, with twice its weight of 
potassium, in a plate glass tube connected with a proper ap- 
paratus, and I heated an equal quantity of potassium alone in 
a tube of the same kind, for an equal length of time, namely, 
eight minutes. Both tubes were filled with hydrogene : no 
gas was evolved in either case. There was no ignition in the 
tube containing the plumbago, but it seemed gradually to 
combine with the potassium. The two results were exposed 
to the action of water ; the result from the plumbago acted 
upon that fluid with as much energy as the other result, and 
