146 Mr. Chenevix's Observations and Experiments 
a leading character may be, their great resemblance to their 
respective species of earthy muriates. I thought, however, that 
I might, if not by direct, at least by double affinity, decompose 
the one without the other ; and phosphate of silver occurred to 
me as the most likely agent. If phosphate of silver be boiled 
with muriate of lime, of barytes, &c. a double decomposition en- 
sues; and muriate of silver, together with phosphate of the earth, 
both insoluble, are precipitated. To increase the action, the 
phosphate of silver may be dissolved in a weak acid, such as 
the acetous ; and, though the earthy phosphate be at first re- 
tained in solution, it will be separated by expelling the acid. 
The only condition absolutely necessary is, that the silver em- 
ployed be free from copper. For, in preparing phosphate of 
silver by phosphate of soda, and by nitrate of silver thus impure, 
copper would be thrown down by the phosphoric acid ; and the 
phosphate of copper would be afterwards decomposed by muriate 
of lime. Muriate of copper would therefore remain with the 
earthy hyperoxygenized muriates ; or, what is still worse, a 
part of the muriatic acid being easily expelled from oxide of 
copper, the hyperoxygenized muriatic acid would be driven off 
from its basis, by the more powerful agency of the former. 
This salt has all the properties enumerated as belonging to the 
genus of hyperoxygenized muriates ; and, with heat, the acid is 
expelled by all acids above the benzoic. I had hoped that, without 
distillation, I could procure the acid from the salt by means of 
sulphuric acid, which would have left an insoluble salt with 
barytes ; but hyperoxygenized muriatic acid is so easily decom- 
posed by light, that I have not yet obtained it, to my satisfaction, 
disengaged and pure. A fact well worthy of attention is, that 
the stronger acids disengage this acid with a flash of light. 
