44 



AK^ALS OF HORTICULTURE. 



remained stable for weeks; and in fact the Bordeaux, as a 

 mechanical mixture, was improved, for the emulsion held the 

 lime in suspension, so that its tendency to settle to the bottom, 

 and thus require constant stirring, was reduced to a minimum. 

 The addition of the Paris green to the Bordeaux before the 

 emulsion was put in, did not visibly affect the mixture. Up to 

 this point, therefore, the combination was a success. It now 

 remained to be seen how it would stand a practical test by the 

 ordinary fruit grower in the field. Theoretically, the chances 

 were all in its favor. 



" However, further experimentation at the Insectary 

 showed that unless the Bordeaux was rightly made, the emul- 

 sion would not form a stable combination with it, and in fact 

 sometimes would scarcely mix at all. It was found that the 

 best combination was obtained when the acid copper sulphate 

 solution of the Bordeaux was exactly neutralized by the alka- 

 line lime; the potassium ferrocyanide was the test to deter- 

 mine when this point was reached. Thus, when the Bordeaux 

 was made in the usual way without testing, nine times out of 

 ten the emulsion would not mix with it satisfactorily. Here, 

 then, was the first obstacle to the Cornell mixture, — the diffi- 

 culty of making it. In the spring I saw it made and applied 

 on a large scale, with horse power sprayers. As far as the 

 making and application were concerned, it was a success. It 

 worked as easily through the sprayer and nozzle as the Bor- 

 deaux alone. But an examination of the trees after the sprayer 

 had passed showed that the mixture had not spread so evenly 

 over the tree as would either of the ingredients alone. And 

 right here, I believe, is the weakest point in the Cornell mixture. 

 The spray was thrown fine enough, but when it struck the trees 

 the minute particles seemed to be drawn together, into larger 

 oily drops, leaving considerable areas unwet. There is a ten- 

 dency in the Bordeaux mixture alone to do this, but it was 

 increased by the oil in the emulsion. . . . 



" When properly made and applied it will be quite effect- 

 ive, each ingredient for the purpose it is intended. But I 

 believe the effectiveness of each ingredient will be greater if 

 they are not applied in combination, but singly. Thus, 

 theoretically, the Cornell mixture has great possibilities, but, 

 besides the difficulty of making, the effectiveness of each ingre- 

 dient is lessened, and in consequence the practicability of the 

 mixture is as yet doubtful, and I cannot freely recommend it 

 for general use." 



Enlisting Children in the Warfare Against Insects has been 

 undertaken in Massachusetts* with gratifying results. Gar- 



* Annals for 1892, 123. 



