Materials and Formulas. 131 



weigh 8.345 pounds. For the same reason the normal mixture 

 may be termed a 1.6 per cent Bordeaux, as the 6 pounds form such 

 a percentage of the weight of the water. This method of desig- 

 nating the various mixtures is the one generally adopted in 

 Europe, and it is convenient here for purposes of comparison. 



Occasionally the recommendation is made to add 1 quart of 

 molasses to the above mixture in order to increase its adhesive 

 properties. As a matter of fact, the addition is rarely made, 

 and is scarcely necessary, since the mixture, even when used 

 alone, is one of the most adhesive of fungicides. The addition 

 of from 1 to 2 pounds of soap has been made for the same 

 purpose, and also to make the mixture spread more evenly. 

 The value of the mixture is slightly increased by such additions ; 

 nevertheless, they are scarcely necessary. 



In Italy the milk of lime is not used in making the Bordeaux 

 mixture, but in its place lime water, which is a saturated solu- 

 tion, is added to the copper sulphate solution. This makes a 

 very dilute mixture, as the following formula of Cavazza shows. 



Cavazza's Bordeaux mixture (Italian) : 



Copper sulphate 720 grams. 



Lime water 100 liters. 



This is a neutral mixture which contains about .072 per cent 

 of copper sulphate. It is very highly recommended in Italy, 

 and Professor Cavazza writes me that he has used the mixture 

 so prepared, since 1886, for controlling fungous diseases of the 

 grape as well as those of the peach, and in general it is there 

 used in preference to other formulas. The French, however, 

 use a mixture having from 1 to 2 per cent of copper sulphate, 

 the milk of lime being preferred to a saturated solution. 



When the Bordeaux mixture is made according to a certain 

 formula, a few points must be observed which it is unnecessary 

 to notice when the ferrocyanide of potassium test is used. The 

 directions given above call for 1 to 2 pounds of copper sulphate 

 to each gallon of water, the smaller amount being preferable. 

 This solution should be diluted one-half before the lime is added. 

 If too little water is present when the two ingredients are brought 

 together, the mixture thickens up like sour milk, and it must 

 be thoroughly stirred to change it to a more liquid form. Such 

 concentrated mixtures are not, on the whole, the best to make, 



