34 INJURIOUS INSECTS OF 1903. 



the carelessness of employes, let us say, that per cent was 

 attained from free arsenic which was not properly combined 

 with the copper. Previous to this year many analyses by 

 different chemists, including the government force at Wash- 

 ington and the chemists employed by these manufacturing 

 firms, gave only the total arsenic in the samples, thus not dis- 

 closing this evil which means so much to the farmer and fruit 

 grower, the report showing there zvas 50 per cent or over of ar- 

 senic, but not all the reports showing in zvhat condition it existed. 



To correct this the New York law was amended in 1900, it 

 now reading "Paris Green shall contain arsenic in combination 

 with copper equal to not less than 50 per cent arsenious oxide. 

 It shall not contain arsenic in water soluble forms to more 

 than 3^ per cent." 



It was to show to Minnesota farmers and orchardists how 

 they were not securing a good grade of Paris Green that this 

 department has purchased different samples of that material in 

 different parts of the state during the year just passed, and in 

 conjunction with the chemical department of the station has 

 determined the nature of the samples purchased. 



The California Experiment Station has brought out this 

 year in a bulletin recently issued, No. 151, the very point we 

 wish to illustrate here; in justice to ourselves it should be 

 stated that our results were obtained before the publication 

 of the Pacific Coast bulletin, though not published until now. 

 As is evident from the nature of it, the bulk of this work has 

 naturally fallen to the chemist, and to him the most credit iS 

 due, this department obtaining the samples, submitting them 

 to one or two simple tests, one of which at least is in the hands 

 of the farmer, illustrating the appearance of some of the adul- 

 terated samples, and bearing the main portion of the expense 

 involved in the analyses. 



The tests employed by the Entomological Department were 

 (a) the microscope test by which the adulterations were 

 made evident ; the microscope unfortunately is not in the 

 hands of many farmers or fruit growers; and (b) the am- 

 monia test, which, though it is not as complete as might be 

 desired, does afford an inexpensive and handy means of de- 

 termining whether Paris Green is badly adulterated with 

 other substances than arsenic or not. Its limitations are dis- 

 cussed below. * 



