3 



The original formula, as published in this country, was Blue 

 Vitriol, 6 pounds ; Lime, 4 pounds ; and Water, 22 gallons. 



This has been found to be much stronger than necessary for 

 effective work, and various degrees of dilution have been rec- 

 ommended. The formulas for the dilute Bordeaux mixture 

 have been almost as numerous as the individual experimenters, 

 While many of them have been practically identical in strength, 

 the different wording and arrangement of proportions have been 

 confusing, so that the movement on foot among experimenters 

 for a simplification of formulas seems wise. 



We think the method of expressing the strength of the 

 mixture suggested in N. Y. Agricultural Experiment Station 

 Bulletin No. 84, page 3, a good one. It is the first publication 

 of the method which Ave have seen, but we have personally used 

 it in our notes and computations for the last two years. This 

 is, in substance, to make some weight of the blue vitriol the 

 unit of the formulas, and to express the strength by the pro- 

 portion of water used with it, it being understood that a sufficient 

 quantity of lime is to be used. The pound naturally suggests 

 itself as the unit of weight for the blue vitriol, and the gallon 

 for the unit of water. 



According to this mode of expression the original formula 

 quoted above, viz., 6 pounds of blue vitriol to 22 gallons of 

 water would be 1 to 3|; 1 to 8 Bordeaux Jiiixture would be 1 

 pound of blue vitriol to 8 gallons of water; 1 to 12 Bordeaux 

 mixture would be 1 pound of blue vitriol to 12 gallons of 

 water. By using this method it is very easy to compute the 

 amount of materials necessary for any given quantity of the 

 mixture. 



The important ingredient of the Bordeaux mixture is the 

 copper sulphate, or blue vitriol. This alone, dissolved in water, 

 would be an efficient fungicide ; but it would so seriously injure 

 the foliage of plants, that the remedy would be worse than the 

 disease. The object of the lime in the Bordeaux mixture is to 

 prevent this injury. This it does, when used in a sufficient 

 quantity, by producing a chemical change in the solution of blue 

 vitriol which renders it harmless. The lime is also of use in 

 Causing the mixture to adhere more strongly to the sprayed 

 foliage, so that it is not quickly washed oft' by rains. 



