172 
Proceedings of the Royal Irish Academy. 
portant to verify, as they bear upon an investigation to be ultimately 
embodied in this report. 
Experiment I. : — 
A saturated solution of lime was formed in the following manner : 
Freshly burned lime was slacked and washed by decantation — distilled 
water being used — the residual lime was then digested with fresh 
water for twenty-four hours, with occasional shaking. This, on sub- 
sidence, constituted the lime water used. It is hardly necessary to ob- 
serve, that all this manipulation was carried on in a stoppered bottle. 
The bright lime water was poured off into a flask, this was brought 
quickly to the boil, and whilst boiling poured upon a filter arranged 
in the following manner : — A glass funnel was placed inside a double 
funnel of tin, the outer space of this double funnel being filled with 
glycerine, which was kept as near the boiling point as practicable. 
(The boiling point of Price's Glycerine" is about 177°— 182° C). 
By this means the lime water is kept as near to the temperature of 
dissociation as possible during the whole of the draining and drying, 
which is only a matter of about half an hour. Hydrate of lime dried 
over sulphuric acid does not suffer loss on being submitted to a similar 
temperature. The precipitate was brushed into a platinum crucible 
and weighed ; it was then ignited, and the loss calculated. 
In two determinations the weighings showed a' considerable reduc- 
tion ; but in both cases this was much under the quantity required by 
a true hydrate. 
Thus— 
Weight of Precipitate, Loss on Ignition. Percentage H3O. 
Theory. Practice. 
First determination, . . -155 gramme, . . -031 . . . 24-33 ... 20 
Second determination, . -131 „ . . '023 ... — ... 17*56 
It is curious to observe that the 2nd determination gives the 
amount of loss required by the formation of a hydrate having the com- 
position 3 QdJ'O ; 2 H^O, viz., 17-64. This experiment was executed 
as rapidly as possible. 
* The following quotations are taken from most of the recent authorities, and 
are all evidently based upon the original experiments of Dalton, published in 1810 
("A New System of Chemical Philosophy, Part II., by John Dalton, Manchester"). 
Dalton gives lime water formed at 60° Faht., as containing 1 grain in 778 grains of 
water, and at 212 Faht., 1 grain in 1270. " Watt's Dictionary of Chemistry," vol. 1, 
p. 718, says, " Hydrate of lime is more soluble in cold than in hot water, hence 
water saturated with lime in the cold, deposits the hydrate when boiled.'" Miller 
says, in his " Elements," Part 2, p. 418, 4th edition, Lime is soluble in about 700 
parts of cold water If lime water, saturated in. the cold, be raised to 
the boiling point, half the lime is deposited." Wurtz, in his " Dictionnaire de 
Chimie," quotes Dalton's experiments, and says, chaux est peu soluble dans 
Vean et elle presente cette particularite qu'elle Vest plus d froid qiC d chaud,'''' &c. 
