I 10 Bulletin N0. 1.47. ,  
30 per cent. of copper oxid. Water-soluble arsenious oxid  
I should not exceed 1.50 per cent. · ` ,
Since the above was written, I have, through the cour— l
‘ tesy of Dr. Brown of the Food and Drug Division of the Sta-  
I tion, examined the results of recently made analyses of four  
. - Kentucky samples of Paris green and find that while _they ,
average 29.57 per cent. copper oxid and 55.82 per cent. ar- .
i senious oxid, they run high in water-soluble arsenious oxid, V .
l the average being 2.73 per cent. ` - ,
_ ARSENATE OF LEAD. s
· The presence of soluble arsenic in Paris green and the
consequent danger of burning foliage with it, has more than
anything else led fruit growers to adopt `arsenate of lead,
I when it can be secured, in preference for use on fruit trees. _
It is not at all hurtful to leaves, and has the further advan- .
tage of sticking, so that, once dri·ed, the spray can be de-
pended on to remain for some time and continue effective
against all gnawing insects. ‘ . ‘
Analyses of the insecticide made at this Station showed
it to contain in the dry material an average of about 65.59 I
` per cent. of lead oxid and 26.58 per cent. of arsenious oxid. . ,
I As put on the market it is generally in the form of a thick
white paste resembling the white lead used by painters. It _
mixes readily with water, when it is ready for use at once. i
The quantity of water present in the paste may range wide-
ly. It should not exceed 50 per cent. In the samples exam-
ined here it averaged about 37.63 per cent. ` I
Professor Colby of California found the arsenious oxid to
range from 8.30 to 14 per cent. in six samples reported by .
him in 1906, the average per cent. being 11.57. ` Seven sam-
ples reported by the same chemist gave an average of 37.64 {
per cent. of lead oxid. Most of them contained a consider- .
able quantity of glucose, and other organic. materials (4.57 `
to 12.70 per cent. with an average of 9.45). The water pres- Y
w