SOLUTIONS FOR SPRAYING 135 



They mix as they run together into the trough and 

 this mixture should be vigorously stirred in the barrel 

 during the operation. The mixture thus completed 

 is drawn off by gravity into the spray tank, passing 

 through the cheesecloth strainer on its way. 



This staging must be made high enough so that 

 the completed mixture will run down into the 

 mounted spray tank; and there must be arranged 

 a convenient water supply sending water easily up 

 to the top platform. This staging can be used in 

 making and handling other sprays, though it is 

 especially adapted to the manufacture of bordeaux. 

 A word needs to be said about the chemicals used. 

 Copper sulphate is seldom adulterated though some- 

 times it is not so clean as it ought to be. The granulated 

 form costs about one-half cent more a pound than 

 the lumps, and is easier to dissolve. If the amount of 

 work to be done will justify it the copper sulphate 

 should be bought by the barrel. A barrel contains in 

 the neighborhood of 200 pounds and costs from 6^4 to 

 7^2 cents a pound at present, with a tendency for the 

 price to go higher. 



The proper selection of lime is more important. 

 The lime must be of good quality, well burned and 

 not air slaked. The fine lime sometimes preferred by 

 masons should not be used. Lumps are better. 



Always use lime enough. The quantity recom- 

 mended in the formula already given will be quite 

 sufficient if good lime is used; but in case of doubt 

 more lime can be used. It is customary in books and 

 bulletins to recommend the so-called ferro-cyanide 

 test, but in actual practice it is better to rely on good 

 lime. The idea of this ferro-cyanide test is to de- 

 termine whether the lime has completely neutralized 



