76 Mr. Davy’s Lecture on some new analytical Researches 
peculiar combustible substance was a non-conductor of elec- 
tricity, I was never able to obtain it, except in very thin films 
upon the platina. It was not possible to examine its proper- 
ties minutely, or to determine its precise nature, or whether 
it was the pure boracic basis ; I consequently endeavoured to 
apply other methods of decomposition, and to find other more 
unequivocal evidences upon this important chemical subject. 
I have already laid before the Society an account of an ex- 
periment,* in which boracic acid, heated in contact with potas- 
sium in a gold tube, was converted into borate of potash, at 
the same time that a dark coloured matter, similar to that pro- 
duced from the acid by electricity, was formed. About two 
months after this experiment had been made, namely, in the 
beginning of August, at a time that I was repeating the pro- 
cess, and examining minutely the results, I was informed, by a 
letter from Mr. Cadell at Paris, that M.Thenard was em- 
ployed in the decomposition of the boracic acid by potassium, 
and that he had heated the two substances together in a copper 
tube, and had obtained borate of potash, and a peculiar matter 
concerning the nature of which no details were given in the 
communication. 
That the same results must be obtained by the same me- 
thods of operating, there could be no doubt. The evidences 
for the decomposition of the boracic acid are easily gained, 
the synthetical proofs of its nature involve more complicated 
circumstances. 
I found that when equal weights of potassium and boracic 
acid were heated together in a green glass tube, which had 
been exhausted after having been twice filled with hydro- 
* Phil. Trans. Part II. 1808. p. 343. 
