‘On definite Proportions. ol 
B. Combinations of Water with Bases. 
le Alkalies and Alkaline Earths. 
The extrication of a quantity of hydrogen gas, during the re- 
duction of the alkalies to a metallic form, by the action of iron 
raised to a white heat, has induced severa! chemists to endeavour 
to discover water in the fixed alkalies after ignition. The results 
of these investigations differ in some measure from each other, 
although they evidently oscillate about the same point. 
Since it is perhaps impossible to obtain a perfectly pure dry 
| caustic alkali, which contains neither carbonic acid, nor earth, 
nor any other foreign substance, so that experiments upon such 
an alkali can afford no very accurate result, I chose for these in- 
vestigations lime and magnesia, convinced that what is true of 
one of these stronger bases, must also be applicable to another. 
| Lime. 
5 _ Some pure well-burnt lime was slaked with water, and strongly 
ignited again in a platina crucible, so that all the carbonic acid 
left in the lime might be expelled with the aqueous vapour. a.) 
Of this caustic lime 10 grammes were slaked with water, dried 
as soon as possible, and lastly heated over a spirit lamp far above 
the boiling point of water. They had acquired an additional 
weight of 3°21 gr. l.) The experiment was repeated with 30 
grammes of pure lime, and afforded 39°75 gr. of slaked lime. 
' Consequently in both these experiments 101) parts of lime had 
. taken up from 52-1 to 32:5 of water. Since in the latter experi- 
, ment the greater bulk of the lime required a longer time for dry- 
ing, it is obvious that the weight must have been increased by 
the absorption of some carbonic acid. But 100 parts of lime 
contain 28°16 of oxygen, and 321 of water 28°5. The slight 
difference evidently depends on the absorption of carbonic acid 
while the lime is drying: and the experiments sufficiently prove, 
that the lime takes up a quantity of water, of which the oxygen 
is equal to that of the earth. 
Magnesia, 
a.) In order to ascertain the quantity of oxygen contained in 
magnesia, | expelled the water of crystallization of some pure 
sulphate of magnesia by heat, dissolved the salt in water, after 
slightly igniting it, and precipitated the sulphuric acid with mu- 
riate of baryta. Ten grammes of ignited sulphate of magnesia 
afforded 19-43 of ignited sulphate of baryta, answering to 6°664 
of sulphuric acid. 
b.) 1 took five grammes of caustic magnesia, which had been 
prepared from the carbonate, precipitated with pure carbonate 
D 2 : of 
