SPEAYIXa APPAKATUS. 



145 



By making a strong application early, the expense of the 

 labor of making the later applications is done away with. 

 Experiments being made by entomologists in different parts 

 of the country will soon indicate the degree of usefulness 

 of this arsenate in destroying different species of native and 

 introduced leaf-eating insects. Practical use in the field 

 later will determine its value as a general insecticide. 



In the field work of the Board of Agriculture the formula 

 of arsenate of lead most used was sodic arsenate, 29.93 per 

 cent., plumbic acetate, 70.07 per cent. Two quarts of glu- 

 cose were generally added to 150 gallons of water to give 

 better adhesive qualities. 



Professor Fernald directs that arsenate of lead can be 

 prepared in the proportion of eleven ounces of acetate of lead 

 and four ounces of arsenate of soda in water. 



Apparatus used for Spraying Large Shade and Forest Trees. 



Fig. 9. Spraying tank. 



The heavy spraying outfits used by the first commission 

 in 1890 were again put in service by the State Board of 



