﻿2 BULLETIN 1147, U. S. DEPARTMENT OF AGRICULTURE. 



The arsenicals analyzed in this investigation, many of which were 

 used in the entomological tests (pp. 26-50), were obtained on the 

 market in 10 1G. The samples were used as purchased, with the 

 exception of the paste products which were dried before being used. 

 Samples of the following arsenicals were studied: Arsenious oxid 

 (4 samples), arsenic oxid (2 samples), acid lead arsenate (18 samples), 

 basic lead arsenate (2 samples), calcium arsenate (9 samples), zinc 

 arsenite (2 samples), Paris green (2 samples), mixture of calcium 

 and lead arsenates (2 samples) , sodium arsenate (2 samples) , potas- 

 sium arsenate (1 sample), London purple (1 sample), and mag- 

 nesium arsenate (1 sample). Several samples of acid and basic 

 lead arsenate and of calcium arsenate, and one of barium arsenate, one 

 of aluminum arsenate, and one of copper barium arsenate mixture 

 were prepared in the laboratory, analyzed, and tested on insects. 



Various names are applied to the arsenicals here designated as 

 (a) acid lead arsenate, (b) basic lead arsenate, (c) arsenious oxid, 

 and (d) arsenic oxid. Some of these names are incorrect because 

 they are based on erroneous analyses or interpretations of composi- 

 tion, for example, ' 'neutral lead arsenate' ' for a basic lead arsenate. 

 Some are considered not to be in good usage, according to modern 

 chemical writing, for example, "arsenious acid" for arsenious oxid. 

 Arsenious oxid dissolved in water forms arsenious acid. The same 

 relation exists between arsenic oxid and arsenic acid. Other names, 

 although correct, are unnecessarily involved, for example, ' 'hydroxy- 

 lead arsenate' ' for basic lead arsenate. The terms selected for use in 

 this bulletin are both scientifically correct and commonly applied to 

 arsenicals. Their names, with the synonyms, are as follows: 



(a) Acid lead arsenate (PbHAsOJ. (b) Basic lead arsenate — Continued. 



Ordinary lead arsenate. Trilead arsenate. 2 



Hydrogen lead arsenate. Nonacid lead arsenate. 



Diplumbic arsenate. Hydroxy-lead arsenate. 



Dilead arsenate. Lead ortho arsenate. 2 

 Diplumbic hydrogen arsenate. (c) Arsenious oxid (As 2 3 ). 



Bibasic arsenate. Arsenic. 



(b) Basic lead arsenate (Pb 4 (PbOH) White arsenic. 



(As0 4 ) 3 . H 2 0). Arsenious anhydrid. 



Triplumbic arsenate (T. P. arsen- (d) Arsenic oxid (As 2 O s ). 



ate). 2 Arsenic pentoxid. 



Neutral lead arsenate. 2 Arsenic anhydrid. 



CHEMICAL PROPERTIES OF ARSENICALS. 



OXIDS OF ARSENIC. 



Arsenious oxid (As 2 3 ), commonly called white arsenic or simply 

 arsenic, is the basis for the manufacture of all arsenicals. In the 

 United States arsenious oxid is a by-product from the smelting of 

 lead, copper, silver, and gold ores, being recovered from the flue dust 

 and fumes. The arsenious oxid first sublimed is impure, owing to the 

 presence of carbon and sometimes of sand. The impure oxid may 

 then be resublimed to give a relatively pure oxicf, consisting of 

 approximately 99 per cent of arsenious oxid and a trace of arsenic 

 oxid (As 2 5 ). Between 11,000 and 12,000 tons of arsenious oxid were 

 produced in the United States in 1920, more than half of which was 



2 These names are incorrect, having been used when basic lead arsenate was considered to be trilead 

 arsenic. 



