﻿ARSENICALS. 



23 



Table 12. — Physical properties of commercial powdered calcium and lead arsenates and 



zinc ar senile. 



Sample 

 No. 



Material examined. 



Total 



arsenic 



oxid 



(As 2 5 ) in 



powders. 



Apparent 

 density. 1 



Suspension proper- 

 ties after stand- 

 ing for 2 — 



10 

 minutes. 



60 

 minutes. 



59 





Percent. 

 45.37 

 47.83 

 40.38 

 41.40 

 49.40 

 40.49 

 39.19 

 31.89 

 32.93 

 31.50 

 32.90 

 32.47 

 32.75 

 » 41. 49 



Qrams. 

 254 

 257 

 364 

 365 

 422 

 532 

 567 

 247 

 249 

 284 

 306 

 369 

 747 

 355 



Cubic 

 centi- 

 meters. 

 245 

 188 

 365 

 380 

 170 

 245 

 170 

 230 

 270 

 110 

 265 

 146 

 88 

 165 



Cubic 



centi- 

 meters. 

 200 

 115 



58 



do 



97 



do 



145 



98 



do 





24 



...do.... 





57 



do 



57 



56 



do 



71 



85 





167 



39 



do 



132 



83 



do 



123 



84 



do 



135 



38 



do 



90 



82 



do 



60 



23 





77 









1 Weight of powder occupying a volume of 1,000 cc. without being jarred. 



3 Based on volumetric readings of 30 grams of powder, shaken with 500 cc. of water and allowed to stand . 



8 Arsenious oxid (AS2O3). 



In Table 12 the calcium and acid lead arsenates are arranged 

 according to their apparent densities, the lightest ones first. The 

 lightest powders usually remained suspended for the longest time 

 (60-minute test) and the heavy powders settled most rapidly. More 

 than 90 per cent of all the arsenicals tested passed a 40-mesh sieve 

 after having been shaken for five minutes. These results are of no 

 value and therefore are not given. It is believed that the fineness 

 of powdered arsenicals, which are generally amorphous, can not be 

 correctly determined by this test, since fine powders pack in a 40- 

 mesh sieve. The fineness of relatively coarse arsenicals, such as 

 arsenious oxid, can be determined by sieving. 



Microscopical examinations of the various arsenicals were made. 

 A large number of samples of powdered calcium and acid lead arse- 

 nates and one of zinc arsenite were blown from a dust gun. These 

 dusts, collected on six or more microscopic slides placed at varying 

 distances from the dust gun, were photographed. Then, using a 

 high-power lens of the microscope, drawings were made by the aid 

 of the camera lucida which made possible the determination of 

 slight differences in the size of particles but did not give satisfactory 

 information on the dusting or spraying properties of these products. 



Several samples of powdered lead arsenate and Paris green, 

 examined under a magnification of 100 diameters, appeared to be 

 amorphous. The samples of calcium arsenate contained a few 

 small crystals, although the samples on the whole appeared to be 

 largely without crystalline shapes. Four samples of arsenious oxid 

 were examined under the microscope. Samples 19 and 27 consisted 

 chiefly of small octahedral crystals; sample 37 contained somewhat 

 larger crystals. 



