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184 THE POTATO 



"The lime used should be white 'fat' lime from 

 the miountaiii limestone or chalk, the kind of lime 

 which is used by plasterers. 'It must be freshly 

 burnt.' If of good quahty eight pounds will be 

 required to neutralize twelve pounds of copper 

 sulphate, but the weight of lime required depends 

 upon the quality, and while as little as six to seven 

 pounds might be suflBcient in one case, as much as 

 ten to twelve pounds might be required in another. 



"2. Preparation: The copper sulphate and 

 lime must always be diluted with a large quantity 

 of water before being brought into contact, other- 

 wise a very inferior mixture will result. When 

 making a small quantity the best plan is to dissolve 

 the copper sulphate in about one half of the water, 

 mix the lime with the other half and then bring the 

 two together; but when a large quantity of spray 

 has to be prepared it is usually much more con- 

 venient to make a somewhat concentrated mixture 

 and to dilute immediately before application to the 

 crop. Under no circumstances, however, should 

 the first mixture be made too strong, and when 

 twelve pounds of copper sulphate and eight pounds 

 of lime are to be employed, the first mixture should 

 fill a forty-gallon cask. To make the mixture, pro- 

 ceed as follows : Run into cask about thirty gallons 

 of water. Crush twelve pounds of copper sul- 

 phate, tie up in a piece of sacking and suspend 

 just below the surface of the water; or, if preferred, 

 dissolve the bluestone in boiling water and pour 

 into the cask. Next moisten and slake eight 

 pounds of lime; the lime must be allowed to swell 

 and crumble slowly; when it has been well slaked, 

 work it down first into a thick cream and gradually 

 dilute to four or five gallons. The milk of lime 

 must next be strained through a fine sieve or piece 



