I36 MAINE AGRICULTURAL EXPERIMENT STATION. I902. 



examined by the U. S. Department of Agriculture, the water 

 soluble arsenic (arsenious oxide) varied from 2.7 to 10.5 per 

 cent. With four exceptions there was less than six per cent of 

 water soluble arsenic in the samples examined. 



The green made by the C. T. Reynolds Company, which is 

 very largely used in Maine, was found by the Department to 

 carry the highest per cent of water soluble arsenic. A sample 

 of Reynolds green examined at this Station was found to carry 

 7.49 per cent of arsenic soluble in water. The amount of water 

 soluble arsenic in the Paris green is of considerable importance. 

 In many states there are laws limiting the amount of arsenious 

 oxide which is allowable in Paris green. In California and in 

 Massachusetts and other eastern states, 4 per cent is the limit. In 

 Idaho 6 per cent has been adopted as the maximum amount. 



As has been pointed out in other publications of the Station, 

 much of the harm of the soluble arsenious oxide in Paris green 

 can be overcome by mixing it with lime water. To be most 

 effectual, it should be mixed with the lime water several days 

 before it is to be used and the mixture occasionally stirred, as 

 the water soluble arsenious oxide goes into solution very slowly. 



If samples of green, particularly in the original package, are 

 sent to the Station they will receive as prompt analysis, free of 

 charge, as is consistent with our other work. The time involved 

 in an analysis is considerable and it is not always possible to take 

 up the work immediately on receipt of sample. 



ARSENATE OF LEAD. 



Arsenate of lead is made by the Merrimac Chemical Company 

 and the Bowker Chemical Company, both of Boston. The 

 Bowker Company sell their output under the name of Disparene. 

 As sold they both carry considerable water, which seems to be 

 necessary in order to make them go readily into suspension in 

 water. They carry from 50 to 60 per cent of actual arsenate of 

 lead, which gives them from 13 to 15 per cent of arsenious oxide. 

 Hence it would take nearly four pounds of arsenate of lead as 

 found in the market to furnish as much arsenious oxide as a 

 pound of Paris green. The arsenate of lead is but very slightly 

 soluble in water and on this account is safer for foliage than is 

 Paris green. In our experiments arsenate of lead was not used 

 with as good results in 1902 as in the two preceding seasons. 



