INJURIOUS INSECTS OF 1903. 



39 



microscope is proven by the chemical analysis, which gives 3 

 per cent of soluble arsenic. Sample No. 12 comes in the same 

 category, while samples 15, 16 and 18 sh^Dw by the various 

 tests not only an excess of free arsenious acid, but also other 

 cidulterants insoluble in ammonia. 



These striking results of our examinations have been ex- 

 plained by a party who is familiar with the manufacture of 

 Paris Green on the ground of the high price of copper which 

 prevailed some time ago, tempting manufacturers to make 

 three tons of Paris Green with an amount of copper from 

 which only one ton should have been made. 



Learning of the results of our analysis of No. 7, the manu- 

 facturers had C. W. Drew, of Minneapolis, analyze a package 

 of their Paris Green purchased on the open market. Mr. 

 Drew's results are here given : 



Fig. 13. — Pure Paris Green as it appears 

 under the microscope. Photographed 

 by J. A. Hummel. 



Fig. 14. — A microphotograph of sample No. 

 7 (see table) showing impurities. Com- 

 pare with Fig. 13. Photographed by 

 J. A. Hummel. 



