154 Remarks on Priestley's Analysis 
cess of weight consisted in water, which the fixed 
air carried off from the menstruum.—But a red 
heat cannot expel the acid from the muriat of ba- 
rytes.* I exposed some of this salt to a very 
strong red heat for two hours; and, examining it af- 
terwards, I found that it had a saline taste, not 
caustic as pure barytes; it precipitated a muriat of 
silver, from the solution of this metal in nitric acid; 
and when concentrated sulphuric acid was poured 
on it, it emitted clouds of muriatic acid vapour. I 
cannot, therefore, admit, that he has demonstrated, 
as he is pleased to say, that one half of the weight 
of fixed air is water; and the following experiments 
will prove, that water enters not into its composition. 
EXPERIMENT I. 
I dissolved 100 grains of aérated barytes in di- 
luted muriatic acid, consisting of one part acid and 
three parts distilled water... The whole being weigh- 
ed before and after the solution, it appeared, that 
18.44 grains of carbonic acid had escaped. The 
barytes was then precipitated from its solution by 
the sulphuric acid. The precipitate, after being 
carefully edulcorated and dried, weighed 121.95 
grains. One hundred parts of this artificial spa- 
chum ponderosum contain, according to Mr. Kirwan, 
67 parts of earth and 33 of acid and water; hence, 
* Gren, Handbuch der Chemie, § 975- 
