No. 6. 



DEPARTMENT OF AGRICULTURE. 



523 



staiu left bv Bordeaux mixture would be objectionable. The solu- 

 tion when properly prepared is perfectly clear and of a very light 

 blue color, which, however, i® practicall}' invisible after it has dried 

 upon the leaves or fruit. For the very late spraying of peaches and 

 phiras against the brown ripe rot it is especially valuable. 



The materials for preparing the solution are copper carbonate 

 powder and commercial ammonia. The first needs no comment, for 



it has not been found adulterated so far as 

 known. If one cares to take the trouble, how- 

 ever, the powder can be prepared at home at 

 about one-third the cost of the commercial arti- 

 cle. The following method of preparing the 

 chemical has been given by Chester in the 

 Annual Keport of U. S. Com. Agric. for 1890.* 

 ^'Dissolve in a barrel twenty-five pounds of 

 copper sulphate in hot water. In another bar- 

 rel dissolve thirty pounds of sal-soda. Allow 

 both solutions to cool; then slowly pour the 

 solution of sal-®oda into the copper sulphate 

 solution, stirring the same. Fill the barrel 

 with water and allow the precipitate of copper 

 carbonate to settle. Upon the following day 

 siphon off the clear supernatant liquid, which 

 contains most of the injurious sodium sulphate 

 in solution. Fill the barrel again with water, 

 and stir the precipitate vigorously into sus- 

 pension; again allow the precipitate to settle, 

 and again on the following day draw off the 

 clear liquid. The operation w^ashes the carbo- 

 nate free of most of the sodium sulphate which 

 contaminates it. Make a filter of stout muslin 

 by tacking the same to a square wooden 

 frame which will just fit over the open top of 

 the second barrel, letting the muslin hang 

 down loosely so as to form a sack; through 

 this filter pass the precipitate, so as to drain 

 off the excess of water, and as the filter fills, re- 

 move the precipitate and allow it to dry in the 

 air, when it is ready for use. The operation is 

 not troublesome, and can be carried on in con- 

 nection with other work By 



'using the above amounts of material there will 

 be formed a trifle over twelve pounds of cop- 

 FiG. 4.t per carbonate." 



•Cited by I.odeman. "The Spraying of Plants," p. 137. 

 tFrom Bulletin 6S of the Illinois Experiment Station. 



