368 



STATE HORTICULTURAL SOCIETY. 



In every instance ammoniacal carbonate was more caustic with Paris 

 green than with London purple. 



These results were unexpected, and could not be accounted for until a 

 chemical analysis of the solutions had been made. Mr. Cavanaugh, assist- 

 ant chemist to the station, found that the ammoniacal carbonate of copper 

 will dissolve practically twice as much Paris green as London purple. 



The larger amount of dissolved arsenic in the Paris green combinations 

 is undoubtedly the cause of the greater injury done by them. 



When these arsenites were applied with the carbonate of copper sus- 

 pended in water, the combination containing London purple was more 

 caustic in every case excepting that of the quince; potatoes were uninjured 

 by either one. 



Conclusions. — When the ammoniacal carbonate of copper is applied in 

 connection with London purple or Paris green, the action of neither the 

 insecticide or the fungicide is weakened. 



The ammoniacal carbonate of copper gave better results as a fungicide 

 when used at the rate of 1-| ounce dissolved in one pint of ammonia, and 

 diluted with 22 gallons of water, than when 3 ounces of the carbonate and 

 1 quart of ammonia were used to the same amount of water. 



The. fungicidal action of the carbonate of copper suspended in water is 

 not marked. 



Even though the ammoniacal carbonate of copper, and the carbonate of 

 copper in suspension, may have no injurious action upon certain plants 

 when used alone, if they are applied in connection with London purple 

 or Paris green, although these are also used in safe quantities, the com- 

 bined action of the two seriously injures the foliage of some of our culti- 

 vated plants. Even when both the fungicide and the insecticide are con- 

 siderably diluted, the injurious action is in many cases serious. 



Paris green with the ammoniacal carbonate of copper is more caustic 

 than is an equal amount of London purple. 



When London purple is applied in connection with carbonate of copper 

 held in suspension in water, the combination is more caustic than one in 

 which an equal amount of Paris green is used. 



Some varieties of certain fruits are apparently more susceptible to injury 

 from the preceding combinations than others. 



None of the above combinations of the ammoniacal carbonate of copper 

 with Paris green in London purple can with safety be used upon the plants 

 treated in this series, with the exception of egg-plants. 



The injury done to foliage by the above combinations is undoubtedly 

 due to the arsenic which is dissolved by the fungicide. 



SULPHATE OF COPPER (COMMERCIAL) AND ARSENITES. 



In order to test solutions of the sulphate of copper in water the follow- 

 ing formulas were made. The tables show the results of the application: 



