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 1916. 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 buUetin are both scientifically correct and commonly applied to 
arsenicals. Their names, with the synonyms, are as follows : 
(a) Acid lead arsenate (PbHAs0 4 ). (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^Og). 
Bibasic arsenate. Arsenic. 
(6) Basic lead arsenate (Pb 4 (PbOH) White arsenic. 
(As0 4 ) 3 . H 2 0). Arsenious anhydrid. 
Triplumbic arsenate (T. P. arsen- (d) Arsenic oxid (A^Og). 
ate). 2 Arsenic pentoxid. 
Neutral lead arsenate. 2 Arsenic anhydrid. 
CHEMICAL PROPERTIES OF ARSENICALS. 
OXTOS 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 oxid, 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. 
