302 Dr. Pearson's Experiments for 
Experiments with Phosphorus applied to mild vegetable Alkali , 
calcareous Earth , Barytes , Magnesia Alba, and Clay. 
Similar experiments to the preceding, made with mild al- 
kali of tartar, in place of fossil alkali, afforded, apparently, as 
much charcoal, and which was easily obtained, but as the phee- 
nomena were similar, and as I have not ascertained with any 
tolerable precision the proportion of the carbonic acid decom- 
pounded, and of the products, it is unnecessary to give any 
further account of them. 
By the like experiments, I endeavoured to decompound the 
carbonic acid in calcareous, barytic, magnesian, and argilla- 
ceous earths. The matter remaining in the tubes, after ex- 
posure to heat, was blackish, and grey, seemingly from char- 
coal being formed, though in much smaller quantity than in 
the preceding experiments with fixed alkalies. For the rea- 
sons above given, I omit the particulars of these experiments 
on earths. 
It appears to me, that the above experiments justify the 
inference that the joint affinities between respirable air and 
phosphorus, and between phosphoric acid and mineral alkali, 
are superior to the affinity between the whole, or at least 
part, of the respirable air of carbonic acid and charcoal, co- 
operating with the affinity between that acid and the same al- 
kali. And, although I have not ascertained the facts with equal 
satisfaction, the experiments already made seem to warrant 
the conclusion, that the order of the affinities is such, that car- 
bonic acid united to vegetable alkali, lime, barytes, magne- 
sia, and clay, will be decomposed by phosphorus in a due de- 
gree of heat. With respect to carbonic acid combined with 
