CALCIUM ARSENATES AND ARSENITES. 91 



This was not a pure material, but the impurities were not of such a 

 nature nor present in such amounts as to be likely to cause injury to foliage. 



Tests of the solubility of this material gave only a trace of arsenic 

 pentoxide as dissolving after twenty-four hours' treatment with water. 

 In order to make a direct comparison of this substance with the pure 

 acid salt, milk of lime was added as described above, and 1.14 pounds of 

 the arsenate were used for each 50 gallons of spray, this amount providing 

 enough arsenic pentoxide to equal that used in the other tests. 



Calcium Metarsenite. — Two samples of this material (both pastes) 

 were tested, having been received from manufacturing companies. Their 

 analyses follow: — 



I_ Per Cent. 



Water, H,0 67.87 



Calcium oxide, CaO . . . . . . . . • .6.78 



Arsenic trioxide, AS2O3 . . . . . . • • . 23 . 87 



Arsenic pentoxide, AsjOs . ■ • • • ■ • • . . 09 



Magnesium oxide, MgO . . . . . • • • . .05 



Sodium oxide, Na20 (estimated) ....... . .70 



Chlorine, CI 80 



Insoluble matter . . . . . . . . . . .01 



100.17 



The original composition of this material was probably about as 

 follows : — 



Per Cent. 



Water, H2O 67.87 



Calcium ortho arsenate, Cas (As04)2 • • • • • • . . 18 



Calcium metarsenite, Ca(As02)2 . • • • • • • .30.31 



Magnesium metarsenite, Mg(As02)i . . . . • • • -30 



Sodium chloride, NaCl . . . . . - • . . 1.32 



Insoluble matter . . . . . . . . . . .01 



This substance gave 11.58 per cent of soluble arsenic trioxide on stand- 

 ing in water for twenty-four hours, showing at once its dangerous nature 

 when applied to foliage. When mixed with milk of lime, however, the 

 amount soluble was greatly reduced, but even then safety could not be 

 obtained with any certaint3^ 



II. Per Cent. 



Water, H2O 79.03 



Arsenic trioxide. AS2O3 . . . . . . . . .16.20 



Arsenic pentoxide, AS2O5 . . . . . . . . . .03 



Calcium oxide, CaO . . . . . . . . . .4.51 



Magnesium oxide, MgO . . . . . . . . . .05 



Sodium oxide, Na20 (estimated) ........ .07 



Chlorine, CI 03 



Organic matter, etc. .......... .08 



Insoluble matter .......... .01 



100.01 



