672 Report oF THE HortTICULTURIST OF THE 
The mixture was prepared according to the plan used the pre- 
vious season. The copper sulphate was weighed, dissolved in 
water and poured into the barrel. The barrel was then filled 
two-thirds full with water, and lime was added in the form of 
thin whitewash until the potassium ferrocyanide test showed 
that a sufficient amount had been used. More lime was then 
added to make sure that there should be no lack of that ingre- 
dient. 
The lime was slacked in a barrel half buried in the ground and 
covered with water to keep it in the condition commonly known 
as “lime paste;” that is to say, chiefly in the form of calcium 
hydrate. No doubt some of the carbonate was gradually formed 
when the lime was kept in this condition, so that some calcium 
carbonate, in all probability, was added each time the mixture 
was prepared. The Bordeaux mixture formed in this way world, 
therefore, probably contain (1) a small amount of copper sulphate 
in solution; (2) basic copper sulphate; (3) double basic sulphate 
of copper and lime, and (4) copper hydroxide,” the last named 
greatly predominating. 
The small amount of copper sulphate in solution that may 
exist in Bordeaux mixture can not be considered sufficient to 
account for the injury resulting from the spray. Granting that 
the basic compounds referred to are more apt to injure the foliage 
than is the hydroxide, which, so far as I know, has not yet been 
proved, there would still be no reason to anticipate trouble from 
this cause, since chemists hold that in the presence of an excess 
of the calcium hydrate but very slight amounts of any copper 
compound, except the hydroxide would be formed in the Bor- 
deaux mixture. 
The copper compound or compounds which give the Bordeaux 
mixture its valuable fungicidal properties are soluble to a slight 
extent in water. Should the ordinary dew or rain water, as it 
occurs on the surface of the leaves and fruit, contain a slight 
amount of carbonic acid, which might be derived either from the 
atmosphere or liberated during the process of respiration by the 
plants, it would have greater solvent action than pure water.” 
23 Fairchild, D.G@. Bordeaux mixture as a fungicide, Bulletin 6, U. 8. Division Vegetable 
Pathology, 1894, pp. 13-15. 
24 The behavior of some vegetable substances toward copper and some of its compounds. By 
E. Formento, Staz. sper. agr. ital. 18, 686-693, cited by Journal Chemical Society, Abstracts, 
vol. LX, p. 491. 
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gem x 
