MATERIALS 37 



easily be mixed with more water in any proportions, 

 such a mixture forming a iiiilk-of-liine : in using this, 

 it should always be run through a piece of sacking or 

 a strainer, to get rid of any grits which may be 

 present. The milk consists chiefly of the fine parti- 

 cles of lime suspended in the water ; when these are 

 allowed to settle, a clear liquid is left, retaining a 

 small portion of the lime actually dissolved in it : 

 this is lime-iuater \ it contains rather more than one- 

 thousandth of its weight of lime. On exposure to 

 the air it becomes cloudy at the surface, owing to its 

 absorbing carbonic acid, and forming chalk. 



For use on a small scale, where additional expense 

 is not a consideration, it will be found very convenient 

 to take pure slaked lime, which may be bought at 

 any chemist's for ^d. to 6cL the lb. It forms a fine, 

 impalpable powder, and its use obviates the necessity 

 of any straining, or even of mixing it with water before 

 adding it to sulphate of copper or iron. It should be 

 kept in a well-closed bottle. The weights of quick- 

 lime given in the above formulae may be taken to 

 apply equally to pure slaked lime, for though the latter 

 contains 27 per cent, of combined water, allowance 

 has been made, in giving the weights of quicklime, 

 for the presence of considerable impurity. 



When a lime-wash is sprayed or painted on to the 

 trees, the deposit of lime soon becomes converted into 

 one of chalk, and it gradually flakes off. The addition 

 of various substances has been tried so as to prevent 

 this flaking, but without much success ; some improve- 

 ment will be obtained by adding to each 10 gallons 

 of lime-wash either 3 lbs. of flowers of sulphur, or 



