on the Nature of certain Bodies. 81 
was still less acted upon by phosphorus, and after an hour's 
exposure to it, had scarcely diminished in quantity, but the 
phosphorus had gained a tint of pale green. 
It did not combine with mercury, when they were heated 
together. 
These circumstances are sufficient to shew, that the com- 
bustible substance obtained from boracic acid by the agency 
of potassium, is different from any other known species of 
matter, and it seems, as far as the evidence extends, to be the 
same as that procured from it by electricity ; and the two 
series of facts, seem fully to establish the decomposition, and 
recomposition of the acid. 
From the large quantity of potassium required to decom- 
pose a small quantity of the acid, it is evident that the boracic 
acid must contain a considerable proportion of oxygene, I 
have endeavoured to determine the relative weights of the 
peculiar inflammable matter and oxygene, which compose a 
given weight of boracic acid ; and to this end I made several 
analytical and synthetical experiments; I shall give the results 
of the two which I consider as most accurate. 
Twenty grains of boracic acid and thirty grains of potassium, 
were made to act upon each other by heat in a tube of brass; 
the result did not effervesce when washed with diluted muri- 
atic acid ; and there were obtained after the process, by slight 
lixiviation in warm water, two grains and about of the olive 
coloured matter. Now thirty grains of potassium, would re- 
quire about five grains of oxygene, to form thirty-five of 
potash ; and according to this estimation, boracic acid must 
consist Gf about one of the peculiar inflammable substance, to 
nearly two of oxygene. 
MDCCCIX. 
M 
