18 



(3) In drjing upon the plant. 



6(CaC03, 2NHri)+6HiO= 3[CaC03, Cn(OH)2] +3(NH4)3C03+6NH, 

 Basic carbonate of 

 copper. 



2[30u(OH)2, 4NH3, 3Hsa]=6Cu(OH)s+8NH3+6H,0. 



From the above formula it is found that to satisfy the reaction, the 

 two pounds of copper sulphate will require 2.3 pounds of crystallized 

 carbonate of soda, which will eventually produce .44 pounds of basic 

 carbonate of copper and .38 pounds of the cupric hydroxide, or a total 

 of .82 pounds of the mixed salts. 



AMMONIACAL COPPER OABBONATE. 



Formula. — Copper carbonate, 3 ounces; strong ammonia, 1 quart; 

 water, 22 gallons. 



In the preparation of this solution, the chemistry is the same as that 

 given under modified eau celeste and the reactions are given in for- 

 mulae (2) and (3). 



Upon the same basis as before, 3 ounces of copper carbonate will yield 

 1.5 ounces of basic carbonate and 1.32 ounces of cupric hydroxide, 

 or a total of 2.82 ounces. The difference between the modified eau 

 celeste and the ammoniated copper carbonate consists in the presence 

 of sodium sulphate in the former material, and its absence in the latter. 

 Whether this sodium sulphate will be at all harmful to foliage is a ques- 

 tion to be decided by experiment, and the writer would advise that this 

 question be tested. The cost of the copper carbonate in the modified 

 eau celeste is approximately 20 cents per pound," while the cost of the 

 commercial carbonate, is, according to present quotations, 65 cents per 

 pound. Furthermore it is seen from the following table that the cost 

 of the basic salts of copper deposited upon the plant, is, in the modified 

 eau celeste, 29 cents per pound, and in the ammoniacal copper carbon- 

 ate 94 cents per pound ; a difference worthy of serious consideration. 



In the use of both the modified eau celeste and the ammoniacal cop- 

 per carbonate there is not produced continually a basic carbonate of 

 copper, but a mixture of the basic carbonate, and the hydroxide. Would 

 it not therefore be well to try the pure basic carbonate either by pre- 

 cipitating the copper with sodium carbonate, and applying it in suspen- 

 sion as the hydroxide is applied in the Bordeaux mixture or by dissolv- 

 ing this precipitate in ammonium carbonate ? By the former method, 

 using 2 pounds of copper sulphate, and 2J pounds of sodium carbon- 

 ate, we would have an extremely cheap and perhaps effective fungicide. 



The following table has been constructed that the facts contained in 

 this paper might be presented in a condensed form. 



The writer in conclusion would particularly recommend that the rela- 

 tive value of the hydroxide, the basic sulphate, and the basic carbonate 



