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_ E
L Insecticides mid Fiwigicides. 9
l
  PARIS GREEN.
g · Thus eight samples of Paris green analyzed in the Divi-
l sion of Chemistry of this Station some years ago ranged
  from 50.16 to 61.5 per cent. arsenious oxid with an average
  of 55.86 per cent. Five samples averaged 25.39 per cent.
I copper oxid, ranging from 8.70 to 30.54 per cent. The aver- 1
A age of this ingredient is lower than it should be because of _
I the deficiency in the sample containing only 8.70 per cent.,
~ which was adulterated with lime, of which it contained 19.48
per cent.
1 The disposition to sell adulterated and inferior Paris
green seems to differ with locality, adulteration in general
1 becoming more prevalent the farther it is from the centers
of manufacture for the product. Thus Dr. Stubbs of Louisi- I
$ ana in 1899 found! that thirty-eight samples ranged from
48.39 to 56.35 per cent. arsenious oxid, with an average of
‘ only 53 per cent. Dr. Traphagen of Montana obtained in
) 1900 an average of 58.57 per cent. arsenious oxid from six
samples, and an average of 30.52 copper oxid.
In California Professor Colby in 1903 found the average of
. arsenious oxid very near what it should be by theory in pure
Paris green (58.65 per cent.), but prior to 1901 in that state,
. it is evident from his analyses, this average was kept up by
a general disposition to adulterate Paris green with white
arsenic. In one sample reported water—soluble arsenic to the
` amount of 29.4 per cent. had been added.
` A veryi satisfactory condition of the insecticide seems to
prevail in New York where Professors Van Slyke and Andrews
(1901) found an average of 58.10 per cent. arsenious oxid in
40‘samples, with a range of 56.13 to 62.87 per cent. The
copper oxid found by these men ranged from 26.53 to 31.14
per cent. and averaged 29.88. Water—soluble arsenious oxid
ranged from 0.88 to 2.64 per cent., averaging 1.28.
A FIRST-CLASS PARIS GREEN.
I From all these results it is safe to hold that a good Paris
green should contain about 58 per cent. of arsenious oxid and