CORRESPONDENCE WITH MANUFACTURERS. 59 



This investigation shows that there are many insecticides on the 

 market which are nearly worthless, and many for which a very exor) >i- 

 tant price is paid that could just as easily be prepared at home. In 

 fact there are very few of the above insecticides which could not either 

 be prepared at home or for which a substitute could not be prepared 

 at a less cost. The only way to obtain information regarding insecti- 

 cides is by consulting bulletins dealing with the subject, or in case the 

 composition of the insecticide in question is not published, to have the 

 same analyzed. 



CORRESPONDENCE WITH MANUFACTURERS. 



In order that manufacturers might have a chance to comment upon 

 analyses before they were published, the following circular letter was 

 sent to each manufacturer whose goods had been examined: 



U. S. DEPARTMENT OF AGRICULTURE, 



BrKEAU OF CHEMISTRY, 



Waxliiii</toii, I). C. 



DEAR SIR: The Bureau of Chemistry is preparing a bulletin giving the results of 

 its examinations of insecticides and fungicides. While we feel sure that the data 

 are practically correct, at the same time we know that one sample does not always 

 represent the products of its manufacturer. We should, therefore, be pleased to 

 have you make any comments that you think necessary on the data as given below. 

 It might be as well for you to know that in our forthcoming bulletin this Bureau 

 has expressed an opinion in favor of a 6 per cent rather than a 4 per cent limit for 

 soluble arsenious acid in insecticides containing this substance. 

 Respectfully, 



H. W. WILEY, Chief. 



The answers to the above letter, where they throw any light upon 

 the subject under consideration, are as follows: 



[Serial No. 19625.] 



We note that the analysis of our Green Arsenoid shows 2.02 per cent sodium sul- 

 phate and 1.30 per cent sand, and we wish to explain that the sand gets into this 

 material from the arsenic which is used in its manufacture. We have been using 

 English arsenic, which at times contains quite a percentage of sand. This does not 

 seem to be the case with the Continental arsenic, which we are now using exclu- 

 sively. The sodium sulphate is, of course, a by-product, and the quantity in the 

 arsenoid is dependent, in a large measure, upon the amount of washing that the 

 arsenoid receives. We believe that the 2.02 per cent is quite exceptional, particu- 

 larly in view of the fact that we are now washing the arsenoid more thoroughly 

 than heretofore. 



ADLER COLOR AND CHEMICAL WORKS. 



[Serial No. 22287.] 



We are in receipt of your analysis of White Arsenoid and would say that this sub- 

 stance is a product which we had used only in a tentative way. There is now none 

 on the market and will be none in the future. 



ADLER COLOR AND CHEMICAL WORKS. 



