320 Magnesian Limestone* 
magnesia give 15,1 grains of ammoniaco-phosphat of magnesia, the 
mixture contains equal quantities of muriat of lime and magne- 
sia. Or, 100 grains so dried are equal to 111 grains chrystallized, 
or 62,2 of dried sulphat of magnesia. But this seems to me be- 
low the average water of chrystallization in sulphat of magnesia, 
which contains nearly 50 percent. 26Nich. Journ. 27 1 . 
This process, is used by Dr. Henry, Dr. Wollaston, and I be- 
lieve by Dr. Marcet. 
4ly. The lime may be precipitated by oxalat of potash, and the 
muriat of magnesia, may be separated either by the filter or by al- 
cohol : and precipitated either by hot carbonat of potash, or by am- 
moniaco-phosphat of soda. Or the alcohol or the acid maybe dri- 
ven off by exposure for an hour to red heat. Or, by sulphuric 
acid, the magnesia may be chrystallized under gentle evaporation 
into Epsom, or the bitter purging salt of magnesia. 
5ly. The muriat of lime, may be precipitated into Gypsum, ei- 
ther by sulphuric acid, or by Glauber’s or Epsom salt acidulated 
with a few drops of oil of vitriol. 
6ly. The limestone containing magnesia, may be reduced into 
an impalpable powder, and treated with an equal weight of oil of ill 
vitriol, mixed with thrice its quantity of water. When the limes- 
tone is well powdered and sifted through fine muslin, and the su- 
perfluous acid driven off by heat, I believe this is as good a me- 
thod as any. 
In making the experiments of which I am about to give the result 
I proceeded in two ways. 
Fzrs£. I took 100 grains of the stone powdered and sifted, and 
treated it with muriatic acid diluted with three waters by measure, 
stirring it frequently after four hours, the supernatant liquor was 
poured off, and the undissolved residuum washed with an equal 
quantity of hot water as of the acid liquor, filtered, and dried in 
the heat of bout 1 60 Fah. and then weighed. 
The solution, was then precipitated by a sufficient quantity of oil 
of vitriol cautiously added : it was left to stand after stirring till the 
gypsum had formed. Then filtered, and the separated gypsum 
put aside. 
This second filtered solution, contained, muriat of magnesia, a 
small quantity of sulphat of magnesia, a small quantity of sulphat 
of lime, and alumina, with excess of acid. The alumina was 
thrown down in a dirty-coloured floculent precipitate, by the cau- 
tion addition of carbonat of ammonia, and was separated by the 
