204 



MANURES. 



Sect. X. 4. 4, 



chemical attra6lIon with the lime, which has been deprived of it by 

 calcination.' 



When mild calcareous earth, as limeflone, chalk, marble, has been 



deprived of its water and of its carbonic acid by calcination, it be- 



comes lime. Afterwards when it is cold, if water be fprinkled 



fiderabl 



by th 

 dies, 

 the h 



ftantly perceived ; which is prelied out 



bo 



mbination of a part of the water with the lime ; as all 

 1 they change from a fluid flate to a folid one, give out 

 which before kept them fluid. At the fame time another 



i3 



part of the water, which was added, is raifed into fteam by the 

 heat given out as above mentioned ; and the expanfion of this fleam 



J lime into fine powder, which otherwife retains the form 



breaks th 



But if too great a quan 



; and th 



of the lumps of limeftone before calcination. 



tity of cold water be fuddenly added, no fleam is raifed 



lump of lime retains its form ; whence it happens, that fome kinds 



of lime fall into finer powder, and are faid to make better mortar, if 



flaked with boiling water than with cold. 



On this account the lime, which is defigned to be fpread on land, 

 fhould previoufly be laid on a heap, and either fufFered to become moifl 



by the water of the atmofph 



water ; otherwife if 

 is expofed to much 



or flaked by a proper quantity of 



be fpread on wet ground 



hen fo fpread 



rain, the heat generated will be diflipated with- 

 out breaking the lumps of lime into powder; which will then gra- 

 dually harden again into limefl:one, difappoint the expedation of the 



a 



and afflid him with the lofs of much labou 



and 



cx- 



pence 



When the powder of flaked lime mixed with fand and water 

 fpread on a wall, that part of the water which is not necefTary for : 



imperfe6l cryflall 



porates into th 



d the lime then 



gradually attrads the carbonic acid, which is diifufed in the atmo' 

 fphere ; but as I fuppofe this carbonic acid is diflTolved in the water 



which is alfo difiufed in 



the atmofph 



the lime is perpetually 



moiflened 



