Sugar and the Bordeaux Mixture. 43 



very slowly and the use of an agitator was almost unnecessary. 

 When applied to the leaves, the preparation was very similar 

 to the Bordeaux mixture in appearance. It adhered to the 

 foliage equally well, and although a large amount of copper 

 was in solution, 240 grams per hectoliter, the foliage was in 

 no case burned. These points appear to have been very thor- 

 oughly tested the same year, for the leaves often remain on the 

 vines until the end of November. 



Michel Ferret was another who made use of this mutual 

 action of sugar and copper. He announced in a meeting of the 

 Societe Rationale d'Agriculture de France held Nov. 27, 1889 

 (page 604 of the proceedings), that in cases of rapid invasion 

 of the mildew the action of the Bordeaux mixture was too slow. 

 He maintained that some copper should always be in solution, 

 and said that he had obtained the desired result by means of 

 sugar or molasses. He used the following formula : 



Copper sulphate 2 kilos. 



Carbonate of soda 3 " 



Water 15 liters. 



The copper sulphate was dissolved in the water, and the soda 

 crystals were then added. When the precipitation of the copper 

 ceased, there was added to the above 



Molasses 200-500 grams. 



The mixture was then allowed to stand twelve hours, and 

 then Ferret added 



Water 1 hectoliter. 



The finished mixture is of a deep green color and is very ad- 

 hesive. His experiments of that year showed that this new 

 mixture preserved the vines better than any other in use at the 

 time. In a letter written later, 1 Ferret says that it suffices to 

 use 200 grams of molasses, or one-tenth of the weight of copper 

 sulphate, to render soluble the amount of copper oxide necessary 

 for the rapid action desired. If a larger amount of molasses be 

 added, the effect is simply to increase the amount of dissolved 

 copper. 



1 Jour. d'Ag. Prat. 1890, Jan. 30, 183. 



