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HOW TO ESTI3IATE THE CUBIC SPACE IN A HOUSE 51 



HOW TO FUMIGATE 



Before fumigating it is necessary to know the amount of 

 space contained in the house ; this will enable the operator to 

 mix his chemicals properly. Hydrocyanic acid gas if used too 

 strong, or if left in the house too long, will seriously injure 

 the plants. It is therefore very important that the directions 

 for treatment be followed carefully. 



The best proportion of cyanide, sulphuric acid, and water 

 seems to be 



1 ounce cyanide of potassium, 



2 ounces commercial sulphuric acid, 

 4 ounces water. 



The water should be poured into the receiving vessel first ; 

 then the acid should be added ; then the cyanide as directed 

 more fully below. Pour the acid into the icater ; never pour 

 the water into the acid. 



In our experiments we used 1 ounce of cyanide to 400 cubic 

 feet of space, and left the house closed but nine minutes. Do 

 not expose the jjlants to the gas longer than this. 



HOW TO ESTIMATE THE CUBIC SPACE IN A HOUSE 



If the house is the shape of a square or a rectangle the 

 cubic contents are found by multiplying the height, length, and 

 width. If the house has a triangular roof with two sides equal, 

 first find the cubic contents of the space enclosed by the walls 

 as directed above ; then find the area of the space enclosed by 

 the roof by multiplying the width of the house by the length of 

 the house and this result by the perpendicular distance from 

 the top of the walls to the gable ; divide this entire product 

 by 3, and add the result to that of the space enclosed by the 

 walls. If, however, the house is irregularly shaped the prob- 

 lem becomes more difficult. The cubic contents may be ob- 

 tained in two wavs : 



a. Divide the house into rectangles, squares, and right 

 angled triangles. The cubic contents of rectangles and 

 squares are obtained by multiplying together the three dimen- 

 sions ; if a right angled triangle by multiplying the two shorter 

 sides together and divide by 2. 



h. The following method, originated by Dr. B. T. Galloway, 

 is quoted from Prof. W. G. Johnson's " Fumigation Methods '* : 



Procure from a stationer a sheet of cross section paper con- 



