g2o Sir H. Davy’s new experiments on some 
combustion 50.9; so that it had increased and this 
increase was in great measure from phosphorus that had 
escaped combustion ; and when this was burnt out by a 
strong red heat, the increase of weight of the tube was 
under J- ; so that at least 5.9 of phosphorus had been con- 
verted into acid : 23.5 cubical inches of oxygen were ab- 
sorbed : thermometer being at 46° Fahrenheit ; barometer 
2 g .6 inches. 
Experiment II. 
Ten grains of phosphorus. The glass tube containing the 
phosphorus weighed 103.1 grains; after the experiment 93.6; 
but much phosphorus remained unconsumed. After the tube 
had been heated to redness, it weighed 94 grains ; so that at 
least 8.4 grains of phosphorus were consumed in the first 
process. The absorption of gas was 34 cubical inches. 
Barometer 29.8, thermometer 47 0 . 
Experiment III. 
Ten grains of phosphorus. By weighing the tube after 
the experiment, and then distilling and burning the residual 
phosphorus, it was found that 9.1 grains of phosphorus had 
been burnt, which had absorbed 35.25 cubical inches of 
oxygen. Barometer 29.7, thermometer 49 0 Fahrenheit. 
I give these experiments as the most accurate I have made. 
The pressure and temperature vary so little, that the correc- 
tions for them are of no importance. Supposing that 100 cu- 
bical inches of oxygen (the barometer being between 29.8 and 
29.6, and the thermometer between 46°and49° Fahrenheit) 
weigh 33.9 grains, phosphoric acid will be composed, accord- 
ing to the first result, of 100 phosphorus to 135 oxygen; 
