a: | oe ae 
15 
scale. Briefly, it consists in inclosing a tree (or nursery stock in greater 
or less quantities at once) with a tent and. filling the latter with the 
poisonous fumes generated with potassium cyanide and sulphuric acid. 
The outfit.—The tents are made of blue or brown drilling or 8-ounce 
duck, and painted or oiled with linseed oil to make them as near air- 
tight as possible. A very convenient form of tent is made in the shape 
of a large hexagonal sheet, which, thrown over a tree, will touch the 
groundon all sides. These sheets or tents are placed over the trees by 
hand or with poles in case of small trees, but with trees over 10 feet 
high some sort of a tripod or derrick is used. The outfit for medium- 
sized trees—tent and derrick—will cost from $15 to $25. <A tent for 
trees 26 feet tall by 60 feet in circumference zosts as much as $60. 
The chemicals—Commercial fused potassium eyanide, 58 per cent 
purity (costing in bulk 40 cents per pound), commercial sulphuric acid 
(at 3$ cents per pound), and water are used in generating the gas, the 
proportions being 1 ounce by weight of the cyanide, slightly more 
than 1 fluid ounce of the acid, and 3 fluid ounces of water to every 150 
cubie feet of space inclosed. 
The method.—The generator, which may be any glazed earthenware 
vessel of 1 or 2 gallons’ capacity, is placed within the tent under the 
tree and the water, acid and cyanide, the latter broken up, put in in 
the order named, after which the operator withdraws from the tent. 
The tent is allowed to remain on the tree for one-half hour for large 
trees or fifteen minutes for small ones. The treatment is best made 
on cloudy days, early in the morning, late in the evening, or at night. 
Bright, hot sunlight is liable to cause injury to the foliage, which, 
however, may be largely avoided by using tents of dark material or 
painted black. 
Three or four men can operate six tents at once, and the expense 
under such conditions, not counting the cost of. the outfit, need not be 
more than 10 cents per tree. One outfit of tents and hoisting apparatus 
will answer for an entire community or county. 
| Bisulphide of Carbon Vapor. 
\ 
In line with the use of hydrocyanic acid gas is the employment of 
the vapor of bisulphide of carbon to destroy insects on low-growing 
plants, such as the lice on melon and squash vines. ‘he treatment, as 
successfully practiced by Professors Garnian and Smith, consists. in 
covering the young vines with small tight boxes 12 to 18 inches indiam- 
eter, of either wood or paper, and introducing under each box a saucer 
containing one or two teaspoonfuls (1 or 2 drams) of the very volatile 
liquid, bisulphide of carbon. The vines of older plants may be wrapped 
about the hill and gathered in under larger boxes or tubs, and a greater, 
but proportional, amount of bisulphide used. The covering should be 
left over the plants for three-quarters of an hour to an hour, and with 
00 to 100 boxes a field may be treated with comparative rapidity. 
