140 The Spraying of Plants. 



Bordeaux mixture. It is also cheap, and on the whole is one of 

 our most valuable remedies. 



Several definite formulas have been recommended for the 

 manufacture of this fungicide, the two following being the best 

 known : 



Copper carbonate 3 ounces. 



Ammonia (22 Beaume) 1 quart. 



Agitate until the copper is completely dissolved. It will 

 keep indefinitely, but should be diluted with 25 gallons of 

 water. 



Copper carbonate 5 ounces. 



Ammonia (26 Beaume) 3 pints. 



"Water 45 gallons. 



The ammonia should be diluted as already described, after 

 which the copper will dissolve more readily. Sixty gallons of 

 water should be used when spraying peaches. 



Combinations of the ammoniacal carbonate of copper and the 

 arsenites are said to have been used with success, but my own 

 experiments have resulted differently. The combination injured 

 foliage to such an extent that it was abandoned after repeated 

 trials. When Paris green was added, the mixture was par- 

 ticularly caustic, since the ammonia undoubtedly caused some 

 of the arsenic to enter into solution. London purple did not 

 make so caustic a mixture, but nevertheless considerable injury 

 resulted, and these combinations may be considered unsafe. 

 The addition of milk of lime,' however, obviates the trouble, 

 and renders the preparation a safe one. Lime to the amount of 

 two to three times the bulk of the poison should be added. 



There are several other mixtures which, in composition, are 

 essentially the same as the solution of copper carbonate in 

 ammonia. They are the modified eau celeste, copper and am- 

 monium carbonate mixture, and Johnson's mixture. Regard- 

 ing these, Chester says, " For all practical purposes, the above 

 fungicides of this group are one and the same, the essential 

 copper salt being, in each case, what for brevity we may call an 

 ammonium copper carbonate, but which is in reality a mixture of 

 ammonium copper carbonate (CuCO 3 , 2NH 3 ) and ammonium 

 cupric hydroxide [3Cu(OH) 2 , 4NH 3 , 3H 2 O]." * 



i Del. Agric. Exp. Sta. kth Ann. Mept. 1891, 68. 



