On definite Proportions. 44l 
Mitrate of Baryta. 
{n order to obtain this salt in perfect purity, I heated it 
to ignition in a silver crucible, dissolved it in water. filtered 
the solution, saturated it with pure nitric acid, and evapo- 
rated it until it crystallized. In order to determine the 
quantity of water of crystallization, which I supposed to 
exist in the salt, | introduced 10 grammes into a small re- 
tort, which instead’ of a receiver was furnished with a tube 
filled with muriate of lime. The nitrate of baryta decre- 
pitated in the heat, and fell into a fine powder: J continued 
the heat until the salt was fused, and began to emit oxygen. 
The retort had now lost +052 gr, and the tube had acquired 
°046. I have shown that the water, which a salt loses by 
decrepitation, can be no water of crystallization, but can 
only be inclosed’ mechanically in the crystals; so that it 
can easily be removed by powdering the salt and by drying 
it in a warm place. It is also to be supposed, for the rea- 
sons which have been given, that crystals, which decrepitate 
in the fire, contain no water chemically combined with 
them. I theretore consider the result of this experiment 
on the nitrate of baryta as a proof, that it contains no water 
of crystallization. 
Ten grammes of finely powdered and very well dried 
nitrate of baryta were dissolved in water in a platina cru- 
cible, sulphuric acid was added, and the mixture was dried 
and ignited. The sulphate of baryta, thus obtained, weighed 
8°867 gr. and, according to the analysis already related, 
contained 5°825 gr. of baryta. Consequently 100 parts of 
nitric acid had saturated j40 of barvta, in which there are 
14°64 parts of oxygen. 
Ten more grammes of nitrate of baryta were dissolved 
in water, and sulphate of ammonia was added to the solu- 
tion, whence were obtained 8-907 gr. of sulphate of baryta, 
containing 5°846 of baryta; so that 100 parts of nitric acid 
should saturate 140°73 of baryta, containing 14°73 of oxy- 
gen. 
Nitrate of the Protoxide of Lead. 
The same appearances, as have been described with re- 
spect to the preceding salt, justify us in concluding with 
respect to this also, that it contains no water of crystallizas 
tion. 
Twenty grammes of finely powdered and very well dried 
nitrate of the protoxide of fead were ignited in a platina 
crucible, and afforded 13°445 or. of protoxide. Conse- 
quently 100 parts of this salt contain 67:2225 of the “abt 
oxide 
