82 Mr. Davy's Lecture on some new analytical Researches 
A grain of the inflammable substance in very fine powder, 
and diffused over a large surface, was set fire to in a retort, 
containing twelve cubical inches of oxygene ; three cubical 
inches of gas were absorbed, and the black residuum collected 
after the boracic acid had been dissolved, was found to equal 
five eighths of a grain. This, by a second combustion, was 
almost entirely converted into boracic acid, with the absorp- 
tion of two cubical inches and one eighth more of oxygene. 
The thermometer in this experiment was at 58° Fahrenheit, 
and the barometer at 30.2. 
According to this result, boracic acid would consist of 
one of the inflammable matter, to about 1.8 of oxygene; 
and the dark residual substance, supposing it to be simply 
the inflammable matter combined with less oxygene than 
is sufficient to constitute boracic acid, would be an oxide, 
consisting of about 4.7 of inflammable matter, to 1.55 of oxy- 
gene. 
These estimations, I do not however venture to give, as 
entirely correct. In the analytical experiments, there are 
probably sources of error, from the solution of a part of the 
inflammable matter, and it possibly may retain alkali, which 
cannot be separated by the acid. In the synthetical pro- 
cess, in which washing is employed, and so small a quan- 
tity of matter used, the results are still less to be depended 
upon ; they must be considered only as imperfect approxima- 
tions. 
From the general tenour of the facts, it appears that the 
combustible matter obtained from boracic acid, bears the same 
relation to that substance, as sulphur and phosphorus do to 
the sulphuric and phosphoric acids. But is it an elementary 
