10 
cent, the arsenic acid from 26.50 to 35.62 per cent, and the calcium 
oxid (lime) from 23.59 to 25.09 per cent. If the arsenious acid and 
arsenic acid are combined and both calculated as arsenious acid, a varia- 
tion of from 37.07 to 40.12 per cent only was noted. Cold water 
dissolved from these samples amounts of arsenious acid varying from 
1.44 to 13.49 per cent and amounts of arsenic acid varying from 7.12 
to 19.56 per cent. 
Since calcium arsenate and calcium arsenite are both, however, 
somewhat soluble in water and since water breaks up both compounds 
to some extent on standing in contact with them, we are not able at 
present to say how much of this arsenic acid and arsenious acid are in 
the free condition and how much combined with the lime.’ It is prob- 
able that plants can bear without scorching larger quantities of these 
soluble arsenic salts than of free arsenious acid. 
LEAD ARSENATE. 
Lead arsenate is prepared by the action of lead acetate on sodium 
arsenate, and of all the arsenicals used as insecticides is probably the 
most insoluble and consequently the least liable to scorch the foliage. 
A recent analysis of a sample of ‘‘Swift’s Lead Arsenate” in this 
laboratory showed that it contained— 
Per cent. 
ead Omid One fo Seas 8 ose id ew Ge cee RE ee ee ee 58,90 tas 
INTSONILG ACTA (2 ee ees re ee oe ea SERS Te tS ES dee 25. 62 
Organi cumatten: jase aaa eee eee eee oe eee eee 13. 00 
The organic portion of the substance was composed almost entirely 
of two sugars—dextrose and dextrin—showing that glucose sirup had 
been added to the lead arsenate to cause it to stick to the foliage. 
Practical tests with this insecticide show that its action is excellent, 
and that on account of its almost entire insolubility it seldom scorches 
the foliage. 
“PINK ARSENOID.” 
Closely allied to lead arsenate is lead arsenite sold by one firm under 
the name of ‘‘ Pink Arsenoid” and prepared by the action of lead 
acetate on sodium arsenite. This substance was found by the Cali- 
fornia Experiment Station (Bulletin 126) to consist of arsenious oxide, 
lead oxide, small amounts of impurities, and a small amount of a pink 
dye stuff to color it. Only 3.24 per cent of the arsenious acid was in 
the free condition. This, next to lead arsenate, is probably as insoluble 
as any of the arsenicals, and according to reports from various experi- 
ment stations has given good results. 
“WHITE ARSENOID.” 
Another of the arsenites—barium arsenite—was recently put on the 
market under the name of ‘‘ White Arsenoid.” This is prepared by 
dissolving arsenious acid in a solution of sodium carbonate and treat- 
