260 



Bulletin 231. 



■^3 



''if.. 



time fumigation with from two to four ounces of cyanide per thous- 

 and cubic feet of space, was found unsafe; and long time or over- 

 night fumigation with one ounce of cyanide to each one thousand 

 cubic feet, was safe only under certain conditions. These conditions, 

 in our experience, are absolute darkness, a still air, a temperature 

 below sixty, and a dry house. With these conditions, it has been 

 possible to keep down the Aleyrode by fumigating once each month 

 with one ounce of cyanide of potassium, two ounces of sulphuric acid 

 and four ounces of water to each one thousand cubic feet of house 

 space. 



Great care is necessary in the use of this gas. No part of the 



handling must be left 

 to chance. Not only 

 should the house in 

 w^hich the gas is 

 generated be locked, 

 but the entire range 

 should be guarded. 

 The gas may escape 

 from one house to 

 the next and is sure 

 death to all animal 

 life. 



How to Fumigate — 



A desirable method 



0f ^^ ., is to fumigate late in 



\ " " '-**?*s» '.-- ": '- the evening when 



there is less likeli- 

 hood of anyone being 

 in, or around the 

 houses. Our practice 

 is to measure the 

 four fluid ounces of 

 water into earthenware vessels. Then measure the acid and pour into 

 the water. Weigh the cyanide and place in thin paper bags. Set 

 the vessel containing the liquid on walks in house. Drop a bag of 

 cyanide in the vessel and walk briskly out of the house. If more 

 than one vessel is used (and in a house containing five thousand 

 cubic feet, two vessels are better), the second bag of cyanide may 

 be dropped in passing, starting with the one farthest from the door. 

 If this fumigation is made before midnight, it might be safe to enter 

 the house next morning in order to raise the ventilators; but it would 

 be better to open them from outside, if possible, thus taking no risk. 



">. 



I 



Fig. 10. 



>#■- 



-Pepper. Desirable for late vnnfer and 

 early spring. £ 



