on the Nature of certain Bodies. 6g 
to the action of diluted muriatic acid over mercury, produced 
exactly three tenths of a cubical inch of phosphuretted hydro- 
gene. 
In a second experiment, one grain of potassium was fused 
with three grains of phosphorus ; in this case nearly a quar- 
ter of a cubical inch of phosphuretted hydrogene was gene- 
rated during the ignition. But from the compound exposed 
to muriatic acid, only one tenth of a cubical inch could be 
procured. 
Now it is not easy to refer the deficiency of phosphuretted 
hydrogene in the second case to any other cause than to the 
supply of oxygene to the potassium from the phosphorus ; 
and the quantity of phosphuretted hydrogene evolved in the 
first case, is much less than could be expected, if both potas- 
sium and phosphorus consisted merely of pure combustible 
matter. 
The phosphoric acid, formed by the combustion of phos- 
phorus, though a crystalline solid, may still contain water. 
The hydrogene evolved from phosphorus by electricity proves 
indeed that this must be the case ; and though the quantity of 
hydrogene and oxygene in phosphorus may be exceedingly 
small, yet they may be sufficient to give it peculiar charac- 
ters ; and till the basis is obtained free, we shall have no 
knowledge of the properties of the pure phosphoric ele- 
ment. 
5. On the States of the carbonaceous Principle in Plumbago, Char- 
coal, and the Diamond. 
The accurate researches of Messrs. Allen and Pepys have 
distinctly proved, that plumbago, charcoal, and the diamond 
