!N'ew York Agricultural Experiment Station. 243 



4. Tlie solubility of Paris green in strong ammonia is a fair test 

 of purity, so far as concerns tlie addition of white arsenic and 

 insoluble adulterants, like barium sulphate, calcium sulphate, etc. 

 In the table above we have indicated those samples that dissolved 

 easily and completely in strong ammonia, making a perfectly clear 

 solution without sediment. These samples were free from white 

 arsenic. Fifteen samples dissolved satisfactorily, while nine sam- 

 ples did not dissolve completely at once, but only on standing for 

 a considerable time, and even then traces remained undissolved. 



5. In general, it may be said that the results of our work in- 

 dicate a very satisfactory condition as to the purity of the Paris 

 green in the market. They do not justify the widespread belief 

 that Paris green is extensively and seriously adulterated. In every 

 instance the arsenious oxide considerably exceeds the legal require- 

 ments. The only material that we have found used as an adulter- 

 ant is white arsenic and this in only one or two cases. In not a 

 single case have we found such materials as sulphates of barium, 

 calcium, etc. 



6. The color of Paris green is changed to such an extent by 

 addition of white arsenic or other similar materials that one can 

 usually detect an adulterated article by its appearance. Paris 

 green of good quality is intensely bright green and uniform. 

 "When adulterated, the green loses something of its intensity and 

 is grayish green and is not always uniform. 



EXAMTNTATION OF ^OSCELLANEOUS ESTSECTICrDES. 



PARAGRENE. 



Two samples of this material were secured, one at Jamestown 

 and one at Geneva. One sample contained 43.34 per ct. arseni- 

 ous oxide and 18.08 per ct. copper oxide; and the other 52.30 

 per ct. arsenious oxide and 21.64 per ct. copper oxide. The ar- 

 senic is present in combination with calcium as calcium arsenite 

 to some extent. The material is a proprietary article and is not 

 put on the market as a Paris green. From the results obtained 



