New YorK AGRICULTURAL EXPERIMENT STATION. 437 
mitted indefinite adulteration by common white arsenic. This 
defect has been corrected by requiring that paris green shall 
contain arsenic im combination with copper equivalent to not 
less than 50 per ct. of arsenious oxide. In ascertaining the 
amount of copper in combination with arsenic it has been 
assumed that all the copper present was so combined, except 
when found in excess. While this assumption is not strictly 
accurate, it answers the purpose, especially when the precaution 
is taken to examine the paris green for water-soluble forms of 
copper compounds. 
In the 44 samples of paris green examined the amount of 
arsenious oxide in combination with copper varied from 50.63 to 
57.60 per ct. and averaged 55.10 per ct., which is about 5 per et. 
higher than the minimum required by law. Only one sample 
fell below the limit, and this was only slighly below. 
5. General conclusion as to purity of paris green in market.— 
Our results indicate a satisfactory condition as to the arsenis 
content of paris green found in the market during 1902, and the 
same can be said as to the amount of water-soluble compounds 
present in the samples examined. 
