174 EXPERIMENTAL FARMS. 



From the excellent results obtained by the use of this fungicide, it may be inferred 

 that this fluid presents the copper compounds in a form which is at once inimical to 

 fungus life and non-injurious to foliage. 



Eau Celeste. 



This fungicide is made by adding ammonia to a solution of copper sulphate. 

 The formula usually given for its preparation is : 



Copper sulphate 1 pound. 



Strong ammonia 1^ pints. 



Water 22 gallons. 



The first action of the ammonia is to precipitate basic copper sulphate (CuS0 4 , 

 2 CuOH 2 ), which, however, soon dissolves in the excess of ammonia present, to form 

 ammonio-cupric sulphate (CuS0 4 , 4NH 4 OH), a deep blue fluid. At the same time 

 ammonium sulphate is produced and remains in solution. 



The evaporation of the fluid leaves upon the foliage basic copper sulphate and 

 ammonium sulphate. 



The fungicides, accordingly, fall into two classes. Bordeaux mixture and Copper 

 carbonate in suspension, on the one hand, apply the copper in a more or less insoluble 

 and precipitated form, while Ammoniacal Copper carbonate and Eau Celeste furnish it in 

 solution. It is probable that the latter provides for a more equal distribution of the 

 copper compounds on the leaves. From a chemical standpoint, it might be inferred that 

 the spraying fluids containing the copper in solution, if made according to correct 

 formulae and applied of the proper strength, would prove more efficacious than the fluids 

 containing the precipitated copper, though a slight variation in the strength of the 

 latter would involve, in all probability, less risk of injury to foliage. They are more 

 expensive and troublesome to make than Bordeaux mixture, and their use is now almost 

 entirely restricted to a late application on grapes, cherries and pears. When the fruit 

 is approaching maturity, the Bordeaux mixture is apt to leave a slight deposit on the 

 fruit, which affects its sale. 



An Investigation to ascertain if Arsenic from Paris green passes into Solution 

 in diluted Bordeaux Mixture and Ammoniacal Copper Carbonate. 



For some time past the practice of adding Paris green to Bordeaux mixture and 

 thus combining the properties of a fungicide and insecticide, has been in vogue with 

 many orchardists. The economy of this method, providing the results of the treatment 

 are satisfactory, is very apparent. 



With a view of ascertaining if arsenic went into solution under such circumstances, 

 the following formula was used : — 



*» 



Copper sulphate 4 pounds. 



Lime 4 " 



Water 50 gallons. 



Paris green 4 ounces. 



This mixture was kept well shaken during the time of the experiment. 



After two days a portion was withdrawn and filtered. The filtrate was free from 

 even traces of arsenic. After ten days, another quantity was withdrawn and similarly 

 treated ; analysis proved the absence of arsenic. 



There is, therefore, no doubt that the arsenic under such conditions remains insoluble, 

 and, consequently, non-injurious to foliage. The tendency evidently is (as pointed out 

 by Kilgore and Gillette) for the lime of the Bordeaux mixture to render insoluble and 

 inert any soluble compound of arsenic that may be present. Indeed the above authors 

 report having largely increased the amount of Paris green added, without injury result- 

 ing to plum and peach foliage. 



Judging, therefore, from a chemical standpoint, the Paris green applied with the 

 Bordeaux mixture should be just as efficacious as when applied alone, and, further, 



