42 INJURIOUS INSECTS OF 1903. 



New York, Aug. 19, 1903. 

 Mr. Fred L. Lavanbnrg, City, 



Dear Sir: In regard to the samples of pure Paris Green given me 

 for analysis, I find your product to contain: 



Combined Arsenious Oxide 5428 per cent 



Uncombined Arsenious Oxide 2.00 per cent 



Copper Oxide 3120 per cent 



On the basis of this analysis, your product is about 99 per cent pure; 

 that is, taking into consideration the acetic acid contained in the Paris 

 Green as copper acetate, which is about 11 per cent. 



There is a definite relationship between copper oxide and arsenious 

 oxide. According to "Newth," it is 23.41 per cent copper oxide and 58.7 

 per cent arsenious oxide; the balance of the copper oxide is combined 

 with acetic acid to form copper acetate. This relation of copper arsenite 

 to copper acetate is variable not to any great extent, but still it is vari- 

 able. If the copper arsenite end of the combination is high, the Paris 

 Green will test high in arsenious oxide and low copper oxide, and vice 

 versa. 



I consider, and think, that most chemists would agree that your Paris 

 Green is a pure article. 



Respectfully. 

 (Signed) AUSTIN J. FARREY, 



Chemist. 



Our chemist, commenting upon the above report, states : 

 "My analyses show only 22.04 per cent of total copper ox- 

 ide ; this includes all of the copper combined with both the ar- 

 senic and the acetic acid. The analysis by Mr. Farrey claims 

 31.20 per cent. The analyses made by myself and by Dr. Drew 

 were from separate packages from the same shipment. These 

 different analyses, if correct, show that the different packages 

 are very uneven in composition. Two of the packages from 

 the same shipment were deficient in copper oxide, and show an 

 excess of arsenic over the copper. To state that part of the cop- 

 per is combined with the arsenic and part with the acetic acid 

 does not alter the total copper oxide content, which, even on 

 the basis of Dr. Drew's analysis, made for the manufacturer, 

 shows a deficit. These analyses, taken as a whole, show that 

 the Paris Green was far from uniform in composition, and 

 that two of the packages were below grade to the extent of 10 

 to 20 per cent." 



It is to be noted that our analyses indicate great variation 

 from bad to good in almost every one of the standard brands 

 examined. 



