New York AGRICULTURAL EXPERIMENT STATION. 453 
DISCUSSION OF RESULTS OF CHEMICAL ANALYSIS. 
1. Total arsenious ovide——In the 22 samples of materials sold 
as Paris green, examined by us, the amount of arsenic, equiva- 
lent to arsenious oxide, varies from 55.83 to 60.80 per ct., and 
averages 57.05 per ct. This average is about one-half of one per 
ct. higher than that found last year, and is about one and one- 
half per ct. below the equivalent of arsenious oxide contained 
in pure copper aceto-arsenite. So far as the total arsenic con- 
tent is concerned, the amount found indicates a high quality 
of Paris green. The variation is about the same as last year 
and, excepting two samples, is within surprising:y narrow limits. 
The lowest amount of arsenious oxide is nearly six per ct. above 
that required by law, viz.: 50 per ct. Were the total amount of 
arsenic present in Paris green the only point to be considered, 
the quality would be regarded as very satisfactory, but we must 
consider at the same time the amount of water-soluble com- 
pounds of arsenic present in Paris green. 
2. Water-soluble compounds of arsenic.—The presence of water- 
soluble arsenic in Paris green is seriously objectionable, owing 
to the fact that soluble arsenic compounds injure foliage. Hil- 
gard, of California, states that in the dry climate of California 
Paris green injures foliage when it contains an equivalent of 
more than four per ct. of arsenious oxide in the form of water- 
soluble arsenic compounds. The water-soluble arsenic most 
commonly occurring in Paris green is in the form of arsenious 
oxide, commercially known as common white arsenic. 
The method of analysis used by us in determining the amount 
of water-soluble arsenic compounds in Paris green should show 
the full amount of such compounds that would be found in 
actual field work where Paris green is mixed with water at the 
rate of one part by weight of Paris green to 1,000 parts of water 
and the mixture used soon after preparation. By longer extrac- 
tion with water, larger quantities of soluble arsenic compounds 
can be obtained; but for our purpose, it is desirable to approxi- 
mate the amount likely to be found in actual field practice in 
