154 



AGRICULTURAL EXPERIMENT STATION. 



Shot, Peroxide of Silicates, and Doyen's Potato-bug Preventive, to 

 determine their relative value in destroying the potato beetle. The 

 Paris Green was applied with an ordinary water sprinkler, using 

 one teaspoonful to two gallons of water, with satisfactory results. 

 The London Purple was applied in the same way, but one table- 

 spoonful to two gallons of water. Results not as satisfactory as 

 with Paris Green. The Peroxide of Silicates and Hammond's Slug 

 Shot were sifted on the potatoes from a small box with a fine wire 

 screen bottom, at the rate of sixty pounds to the acre. The for- 

 mer scorched the leaves. Both killed the beetles. A partial 

 analysis was made of Doyen s Potato-hug Prevevtive but no experi- 

 ments were performed with it at the station, though some of it was 

 tried about Orono with negative results. 



In all of these the poisonous ingredient must be arsenious acid 

 (oxide) or its compounds, so that in each case the value of the 

 preparation as an insecticide is determined approximately by the 

 amount of arsenious acid present. The following are the results of 

 the aualvses of the above named materials. 



Arsenious Oxide (white arsenic) 



Cupric Oxide 



Calcium Oxide (lime) 



•Sulphuric Acid (anhydride) .. .. 



Carbonic Acid 



Acetic Acid 



"Dead oil" (by difiFerence)* . . 



Insoluble residue 



Water of hydration (calculated) 

 Moisture 



Oh > 



O 3 



Qffl 



19.09 

 7.41 



* Also determined approximately. 



The Paris Green is mainly an aceto-arsenite of copper, or in 

 other words, a compound of acetic acid, arsenious acid and copper. 

 The London Purple is composed mainly of arsenite of lime, contain- 



