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OFFICIAL RKPORT OF THE PROCEEDINGS OF THE 



Danger from Arsenical Adulterations. — White arsenic (arsenious 

 oxid), as has long been known, is very injurious to foliage; for this 

 reason, it is scarcely at all used for the destruction of insects. It is 

 much cheaper than Paris green, and were it not for the injury to foliage 

 would have been used entirely instead of Paris green. The one thing 

 which has made the latter the standard insecticide has been its 

 insolubility. Of late years, since the addition of free white arsenic has 

 become a common practice by the manufacturers, or by adulterators, 

 the unreliability of Paris green in its influence on foliage has been 

 repeatedly noticed. In the hands of the farmer this is almost sure to 

 result in a diminution of the dose until the injury becomes unimportant. 

 On the farm it is the practice to weigh and measure things very care- 

 lessly, and the difference between full measure and scant measure, even 

 when the farmer thinks he is following directions, amounts to a very 

 great deal. The diminution of dose has been one of the causes, and an 

 important one, of the complaints of the ineffectiveness of Paris green, 

 which we have heard from all over the United States during the last 

 few years. 



The danger to foliage from free arsenic has also resulted in the change 

 of the formula now usually recommended, by attempting to neutralize 

 the soluble substances in the Paris green by the addition of lime. This 

 matter will be referred to again below and in more detail. The addition 

 of lime has been more or less successful when the amount of arsenic was 

 not too large, but one of the great advantages of Paris green — that 

 which more than anything else has caused it to hold its own as an 

 insecticide — is the fact that no preparation is necessary. The substance 

 as it is purchased from the store is stirred up in water and is at once 

 ready for use. If it is necessary to add some material to neutralize the 

 free arsenious oxid, it will be better to take slightly more trouble and 

 decrease the cost of - the material by the use of home-made arsenites. 



Cause of Injury to Foliage. — While Paris green is entirely insoluble 

 in pure water, it appears that as ordinarily used a certain amount of it 

 does find its way into solution and thus enters the plant; and if very 

 much goes in, the death of the part of the plant thus poisoned ensues. 

 The most critical period seems to be the time during which the spray 

 remains wet upon the leaf, and each subsequent wetting of the leaf 

 from any cause, such as a fog or dew, continues the danger. It has been 

 demonstrated repeatedly that dry Paris green can be placed upon a leaf 

 in any quantity, and so long as the leaf remains dry no evil results will 

 follow. After an application in the wet way, almost immediately, within 

 twenty-four hours, a blackening of the leaf or of parts of the leaf may 

 occur, or the leaf may entirely escape at that time, but later, after a 

 dew or fog, show the signs of the action of the poison; or again, there 



