REPORT OF COMMITTEE ON PUBLICATION 159 



Bordeaux mixture 1:1 that produce more slowly settling washes than the 

 so-called standard or American method, i. e., diluting equally the copper 

 sulphate and the milk of lime and pouring them together simultaneously. 

 Do these four methods of mixing produce more adhesive or less adhesive 

 mixture than the standard method? As regards one of them, the addition of 

 strong lime to weak copper, the figures obtained by Gastine indicate that 

 it is slightly less adhesive, but in the matter of the other methods we are 

 at present without data. 



Table IX. Relative rate of settlement at the end of two hours of 1 per cent 

 Bordeaux mixture (1:1) prepared in various ways. 



Method 123456789 



Settlement % 45.07 14.72 17.07 11.34 15.35 13.69 10.5 29.1 52.75 



Besides the method of mixing employed, the temperature of the water 

 used in preparing Bordeaux mixture has a marked influence on the rate of 

 settlement of the preciptate. Taking 1 per cent Borbeaux mixture (1:1) 

 as an example we find that the cooler the water the slower the rate of 

 settlement, the results obtained for a temperature range between 15 C. 

 and 30 C. being extremely striking as is shown in the following table: 



Table X. Effect of temperature of water on rate of settlement of 1 per 

 cent Bordeaux mixture (1:1). 



Temperature 15 C., settlement after: % hour, 3.5; 1 hour, 8.5; 2 hours, 18 

 Temperature 24 C., settlement after: % hour, 6.8; 1 hour, 14.5; 2 hours, 28.2 

 Temperature 30 C., settlement after: % hour, 9.5; 1 hour, 21.25; 2 hours, 38.2 



VI. 



I said in the beginning that a copper fungicide must possess to a high 

 degree the following five characteristics: 



1. The wash must not be toxic to the plant it is destined to protect. 



2. The active principle must be efficient, that is, the unit copper must 

 have a high fungicidal value. 



3. The active principle must be effective, that is, the unit copper must, 

 have a high protective value. 



4. The active principle must be adhesive. 



5. The active principle must dissolve sufficiently rapidly under the 

 action of the weather to be efficient. 



and the milk of lime diluted to 30 cc.; the milk of lime was then poured 

 into the cupric sulphate solution, and water added to 100 cc. In method 2 

 the stock solution of cupric sulphate was diluted to 85 cc., the freshly slacked 

 lime to 15 cc.; the milk of lime was then poured into the cupric sulphate solu- 

 tion. In method 3 the cupric sulphate solution was made up to 15 cc., and 

 the milk of lime to 85 cc. The milk of lime was then poured into the solution 

 of copper sulphate. In method 4 the stock solution of cupric sulphate and 

 the milk of lime were both diluted to 50 cc. ; the milk of lime was then 

 poured into the cupric sulphate. In method 5 the reagents were diluted as 

 in method 4 and were simultaneously poured into a third vessel. Method 6 

 is the converse of method 4. Method 7 is the converse of method 3. Method 

 8 is the converse of method 2. Method 9 is the converse of method 1. 



