Dr J ohn Davy on the Slaking of QuicMime. 17 



produced. After about a quarter of an hour it |^became 

 warm, but quite bearable ; portions fell off one after an- 

 other, but no high temperature was produced. When cool, 

 it was again weighed ; its weight was now 93-8 grs. ; so 

 it had gained only 5*5 grs. of water. The portions which 

 had fallen off, put into water, were some minutes before 

 they became hot ; then they fell to powder, and became a 

 thick paste. 



6. A piece of quicklime, weighing 310 grains, was kept 

 an hour and a half in a close vessel with some damp paper. 

 During this time it had increased in weight only half a 

 grain. Now added gradually, in about half a minute, 19*5 

 grains of water. The water, in minute quantity, was applied 

 successively to different parts of the mass. There was no 

 sensible increase of temperature ; 13*5 grains more of water 

 were added ; still no increase of temperature. After twenty- 

 four minutes 6 grains more were added, without percep- 

 tible effect ; and an hour later 6 more, making a total of 45 

 grains. Shortly after some action had taken place, and 

 a portion had fallen to powder with evolution of heat ; next 

 morning the whole mass was found broken up and reduced 

 to the state of powder. 



7. To 76 grains of quicklime reduced to fine powder, 

 11 grains of water were added in two portions, triturating 

 the powder on each addition. I am not aware of any hesi; 

 having been produced, nor did I see indications of an^ 

 action. The dry powder was put into a tube and tightly 

 corked. On the day following there was no perceptible 

 change. Now added water in great excess, so as to form a 

 thick paste. After a few minutes there was a slight increase 

 of temperature ; after twelve, it had become moderately 

 warm, and it continued so some time, showing the slow for- 

 mation of the hydrate. 



Do not these results warrant the" conclusion, that lime is 

 capable of uniting feebly with less water than is required 

 to form the hydrate, that consisting of one proportion of 

 each, the weaker compound containing probably two propor- 

 tions of lime. In the last-mentioned experiments the quan- 

 tity of water was nearly in accordance with this compo- 

 sition. 



NEW SERIES. VOL. XIX. NO. I. JANUARY 1864. C 



