S MISC. PUB. 526, U. S. DEPT. OF AGRICULTURE 
be prepared, the former at 1 pound per gallon, the latter at 114 
pounds per gallon. These must be stored in tightly covered earthen- 
ware, wood, or glass containers. Equal quantities (the lime suspen- 
sion being well mixed before the measured volume is removed) of 
these preparations can then be diluted, each to one-half the volume 
desired, and mixed to form bordeaux mixture. One gallon of fin- 
ished mixture will require 114 cupfuls of each preparation; 8 gallons, 
1 quart of each. 
Caution.—Bordeaux mixture may cause gastric disturbances if 
taken internally. All unused portions should be disposed of or 
covered so that they will be inaccessible to children and animals. 
It is also somewhat irritative to the eyes and skin. 
CALCIUM ARSENATE 
Commercial calcium arsenate sold for insecticidal purposes, unlike 
lead arsenate, is not a single chemical compound but a complex mixture 
of several arsenates and an excess of lime, whose proportions vary con- 
siderably between brands and even between different lots of the same 
brand. However, it usually contains the equivalent of from 40 to 42 
percent of arsenic pentoxide. Calcium arsenate absorbs carbon 
dioxide slowly from the atmosphere during storage and increases its 
content of water-soluble arsenic oxide, unless it is packed in containers 
that are practically airtight. This change, however, is relatively 
unimportant, 
The domestic manufactured calcium arsenate is a white powder, 
but when sold as an insecticide it is usually colored pink for the purpose 
of marking it asa poison. It is used as a spray at the rate of 114 to 3 
pounds per 100 gallons of water, in much the same manner as lead 
arsenate (p. 16), but it is more generally employed as a dust. As a 
dust it is used principally and in immense quantities in the undiluted 
form on cotton to control the boll weevil. Likewise in the undiluted 
form as a dust it is one of the best controls for the tomato fruitworm. 
Calcium arsenate is sometimes used for the control of cabbage cater- 
pillars, the Mexican bean beetle, Colorado potato beetle, pepper 
weevil, codliing moth, apple maggot, grape rootworm, grape berry 
moth, and cherry fruitfly, and to a limited extent on flowering plants. 
Applications on peppers, potatoes, cabbage, and cotton may result in 
heavy aphid infestations. It is more likely to injure foliage than is 
lead arsenate, but it is less objectionable from a residue standpoint 
because of the absence of lead. It is less effective than lead arsenate 
against the codling moth. Since it is likely to cause foliage injury, 
three or four times its weight of hydrated lime is often added to 
render it safer to use. 
Caution.—Like all arsenical compounds, calcium arsenate is 
very poisonous to man and higher animals, and should be clearly 
labeled and stored away from any food products. It should not 
be applied to the edible parts of fruits and vegetables unless a 
long period intervenes before harvest or unless acid washes are 
used to remove the arsenical. 
CALCIUM CYANIDE 
Calcium cyanide (Ca(CN),.) reacts with moisture in the air and 
gives off the deadly poisonous hydrocyanic acid gas that is toxic to 
