sa6 Dr. Pearson’s Experiments and Obfervations 
4. That the fubftance in the nitrous folution of the part of 
James’s Powder that had been difiblyed in water, which pre- 
cipitates lime from lime-water,' and which precipitate is not 
-Soluble in a large quantity of vinegar, is, probably, phofphoric 
acid from phofphorated lime decompofed by nitrous acid. 
The precipitation by muriated barytes and nitrated filver 
could not be from vitriolic and marine acids confidently with 
the preceding experiments ; and I could not have conje&ured 
what was the ingredient in James’s Powder which occafions it, 
if 1 had not found, that muriated barytes is not only a teft of 
vitriolic but of phofphoric acid united to lime and alkalies ; 
and the acid of phofphorus will alfo produce a turbid appear- 
ance with nitrated filver. The calx of iron, in the above 
experiments, is in perhaps too fmall a quantity to be confidered 
in any other light than as an accidental fubftance. 
II. With acetous acid. 
The 260 grains of James’s Powder, remaining after boil- 
ing 300 grains of it in diflilied water, and after the una- 
voidable wafle of it in the above experiments with water, 
were put into a tubulated retort that would contain fourounce- 
meafures, 011 which were poured three ounces of concentrated 
acetous acid, the fpecific gravity of which was as 106 to 100, 
the neck of the retort being immerfed in quickfilver, and the 
tubulated part being immediately clofely Hopped. No effer- 
vefcence was perceived ; nor did any elaftic fluid rife during 
twenty-four hours into an inverted veflel of quickfilver ; and 
when heat was applied to boil the acid, nothing but the com- 
mon air of the retort and a little water and acetous acid came 
over. 
7 
This 
