16 Dr John Davy on the Slahmg of Quicklime. 



adverted to, ten grains of water were added. The whole of 

 the water was absorbed. As I held it, a very slight sensa- 

 tion of warmth was perceived by the fingers in contact with 

 it — a sensation that occurred immediately, and for about 

 eight minutes it did not distinctly increase. About that 

 time small cracks began to appear at the surface of the 

 piece ; the temperature instantly sensibly rose, and in 

 another minute tlie heat became too great to be bearable. 

 Now, put down, in a few seconds it became rent, and the 

 hydrate was formed. 



2. In a piece of lime of two or three pounds, a hole was 

 bored an inch and half in depth, sufficiently large to admit 

 the bulb of a thermometer. Water, no more than the lime 

 could absorb, was next poured on the mass. The thermo- 

 meter, from 55°, immediately rose to 70° During about 

 eight minutes little change of temperature was observed ; 

 then, in less than a minute, the thermometer rose to 280°, 

 accompanied with the production of steam and the falling 

 to pieces of the mass. 



3. Into a small receiver, 2 J inches high, 1^ inch in dia- 

 meter, quicklime in fine powder (just pounded) was put in 

 sufficient quantity to fill it to about two-thirds. A ther- 

 mometer then introduced stood about 60°. Next added 

 water, more and more, till the whole of the lime appeared 

 to be moistened. This done, in about half a minute, the 

 thermometer stood at 80° ; in about five minutes it had 

 fallen to 78° ; then it began to rise ; in one minute it had 

 risen to 100°, in less than half a minute more to 120° ; then, 

 after a few seconds, an explosion took place, the thermo- 

 meter was throw'n out and the lime was scattered, some 

 even beyond twelve feet. 



4. Into the same receiver about the same quantity of 

 pounded lime was introduced with excess of water, and the 

 mixture was immediately stirred. The lime subsided on 

 rest ; there was about one- tenth of an inch of superincum- 

 bent water. After about twenty minutes the temperature 

 had become a little higher ; in about five minutes more 

 steam was produced, but there was no explosion. 



5. To a piece of quicklime, weighing 88*3 grs., 9*2 grs. 

 of water were added. A slight increase of temperature was 



