70 INJURIOUS INSECTS OF IQ0Q9 AND IQIO. 
or some multiple of that number, is a good size). This is necessary 
in order to compute the amount of chemicals. A means of top ven- 
tilating from the outside should not be omitted. A false floor, if a 
house is used, or a false bottom, if a box is made, lattice-like in each 
case, should be so placed that the trees or scions can be placed 
thereon, an earthen crock or crockery bowl to hold the chemicals 
being placed beneath. Hydrocyanic acid gas is lighter than the 
atmosphere, and the reason for placing it below is to allow the fumes 
to ascend through the stock. Purchase the best of chemicals. The 
cyanide of potash should be 98 per cent purity, practically chemically 
pure, and the sulphuric acid should have a specific gravity of 1.82. 
Do not use cheap chemicals, and insist upon getting what you ask 
for. Wholesale houses in St. Paul can supply the proper materials. 
Cyanide costs about 25c per lb., sulphuric acid from tc to 2c per th. 
If scions or roses or two-year-old apple or plum stock are to be 
fumigated, use the following proportions: Potassium cyanide, % 07, ; 
sulphuric acid, 1% ozs., and water 3 ozs. for every 100 cubic feet of 
enclosed space. Place the water in receptacle above referred to 
(never use a metal dish), add the acid, and then drop in the cyanide. 
immediately closing up the house or box. Allow it to remain closed 
for forty minutes, then open ventilator and air for 15 minutes before 
taking out stock. Not only is cyanide of potash of itself very 
poisonous, but the above gas is deadly if breathed. Hence the need 
of extreme care in handling the cyanide, and in making the gas. 
The former should be kept in an airtight receptacle plainly labeled 
“POISON,” and out of the reach of children; and one should alwavs 
bear in mind that when this cyanide comes in contact with the acid, 
a deadly gas is immediately given off, one good whiff of which 
might be fatal. 
It is best that all stock be dry, or practically so, when fumigated. 
Do not fumigate stock which for any reason is dripping wet. 
Spraying. 
It is to be hoped that it may be some time before Minneso'a 
orchardists have to spray for the San Jose Scale, but since there is 
a wash or spray which is most effective, not only for the San Jose 
Scale, but for all others, we give it herewith. It is known as the 
Boiled Lime Sulphur Wash, and it is to be used only chen the trecs 
are dormant. Make 18 pounds of powdered sulphur (flowers of sul- 
