138 The Spraying of Plants. 



By using the above amounts of material, there will be formed 

 a trifle over 12 pounds of the carbonate of copper, the selling- 

 price of which is about forty cents a pound. When thus made 

 at home, the cost is only about fifteen cents, which is a great 

 saving, especially as the material is nearly chemically pure. 



Copper carbonate is a fine, bluish-green powder, insoluble in 

 water. It dissolves readily in ammonia, forming the ammoni- 

 acal solution of copper carbonate, which see. The powder 

 has often been used as a fungicide when suspended in water, 

 but the results obtained have almost invariably been unsatisfac- 

 tory. When applied in this manner, however, the following 

 formula will prove most satisfactory : 



Copper carbonate 1 pound. 



Water 40 gallons. 



The liquid should be agitated frequently to prevent the cop- 

 per compound from settling to the bottom. The cost of copper 

 carbonate varies from thirty-five to sixty cents per pound. 



COPPER CARBONATE, AMMONIAC AL SOLUTION ; CUPRAM. 

 Penny 1 has made a very careful study of the best method of 

 preparing this solution, and the results of his work are here 

 given in full : 



" The practical directions then are these : To 1 volume of 

 26 Beaume ammonia (the strong ammonia of commerce) add 

 from 7 to 8 volumes of water. Then add copper carbonate, 

 best in successive quantities, until a large portion remains un- 

 dissolved. The mixture should be vigorously agitated during 

 the solution and finally allowed to subside, and the clear liquid 

 poured off from the undissolved salt. A second portion should 

 then be made by treating the residue of the former lot with 

 more ammonia diluted as before, then with the addition of 

 fresh copper carbonate, in every case with vigorous stirring or 

 agitation. This method of making in successive lots will result 

 in a richer solution of copper, at least, unless an unwarranted 

 length of time be taken. This solution may be made in any 

 suitable wooden or stoneware vessel. 



"A still better way is to place in a large jar an inverted 



1 The chemistry of this solution has been thoroughly treated by C. L. Penny, of 

 the Del. Agric. Exp. Sta. an account of which may be found in Bull. 22. I have 

 also quoted freely from other bulletins of the same station on these subjects. 



