POISONOUS METALS ON SPRAYED FRUITS AND VEGETABLES. 3 
remedy against the cabbage worm, applying "-just enough to make a 
slight show of dust upon the leaves." These discoveries were quickly 
adopted in practice, and ^arsenicals were generally accepted as the 
best destroyers of external chewing insects. 
The most important insecticides recommended, other than Paris 
green and London purple, were Scheele's green (113) in 1875, white 
arsenic plus lime (67) in 1891, and lead arsenate (40) in 1893. Until 
recently Paris green and lead arsenate have been the most extensively 
used, but calcium arsenate, now on the market, promises to become 
one of the leading arsenical insecticides. 
The use of Bordeaux mixture originated in France near the city of 
Medoc. Viticulturists noticed that the vines near the highways, 
which had been sprinkled with a paste of milk of lime and copper 
sulphate to prevent thieving, did not suffer from mildew. Prof. 
Millardet, in 1882, attributed the beneficial action to copper, and later 
proposed a mixture of copper sulphate, lime, and water, since known as 
Bordeaux mixture (88) (89) . The mixture was immediately accepted 
not only in France but in the United States, where F. Lamson 
Scribner (116) was probably the first to publish a formula for it as a 
result of the work in France. Its use has been extended to the preven- 
tion of so many plant diseases that to-day it is perhaps the most 
important fungicide. 
When copper compounds were recommended as fungicides, the 
question arose as to whether or not spraying with them would leave 
a dangerous amount of copper on the grapes or in the wine. 
Perrett (107) stated, in 1885, that there would be no danger of 
introducing copper into wine made from grapes sprayed with copper 
salts, because the hydrogen sulphid formed during fermentation 
would precipitate the copper as the insoluble sulphid. Quantin (111), 
in 1886, concluded that the reduction of the sulphate of copper by the 
ferments was sufficient to effect the total elimination of the copper 
in wine, but that aeration of the lees which inclosed the precipitated 
sulphid of copper should be avoided. Chuard (23) announced in 1887 
that the copper was present in the must as copper malate, but that it 
was precipitated during fermentation as the sulphid and tartrate. 
In October, 1885, Millardet and Gay on (90) obtained the following 
amounts of copper from vines that had been sprayed with Bordeaux 
mixture in July: 
Fresh leaves (mg. per kgm.) 19. 1-95. 5 
Vine branches (mg. per kgm.) 5. 8 
Grape stalks (mg. per kgm.) 15. 0-18. 6 
Marcs (mg. per kgm.) 11. 1-21. 9 
Musts (mg. per liter) 1. 0- 2. 2 
Wines (mg. per liter) , f r jm doubtful traces to less than 0. 1 
