42 MISCELLANEOUS PAPERS. 



hops, which do not come into direct contact with the gases or fumes 

 from the fires. From the experiments cited the conclusion is drawn 

 that hops dried by the indirect process are arsenic free. 



It is known, however, that traces of arsenic sometimes occur in hops 

 which have been dried by the indirect process, a condition which has 

 been urged in England as an argument against the purchase of im- 

 ported hops, thus rendering more difficult the sale abroad of those 

 grown in the United States. 



Since under the ordinary conditions of hop production in the 

 United States there is a surplus which requires an annual exportation 

 of a considerable portion of the crop, & it is highly desirable that this 

 product be prepared in every way free from deleterious substances 

 which would interfere with its sale and use abroad. 



During a recent study of the processes of curing and sulphuring 

 hops c some experiments were made to determine the most probable 

 source of arsenical contamination. The possible sources include fuels, 

 arsenical sprays, the soil, and sulphur both when used in the field to 

 destroy pests and when burned under the hops on the kiln during 

 the drying process. 



Since the open-fire, or " direct," process of drying is never used in 

 this country, and as traces of arsenic have been found in hops not 

 treated with insecticides, only the soil and sulphur were considered 

 in these experiments, which, though not fully complete, have yielded 

 results of so much importance to American hop growers that they 

 are here presented in preliminary- form. 



ORIGIN OF SAMPLES OE HOPS EXAMINED. 



The geographical distribution of hops containing traces of arsenic 

 was first investigated. Dry commercial samples were obtained from 

 England, Belgium, East Prussia (Altmark), Bavaria, Bohemia 

 (Saaz), British Columbia. Xew York. Wisconsin, and the Pacific 

 coast. Upon analysis d small quantities of arsenic (1.5 parts to the 

 million, or less) were detected in samples from each of the regions 

 just mentioned. These results indicate that hops from any of the 

 hop-growing districts of the world may contain traces of arsenic, and 

 suggest the necessity for the thorough examination of hops whatever 



a Duncan, C, loc. cit., p. 24. 



6 Merritt, E. Bui. 50. Bureau of Statistics. U. S. Dept. Agriculture, table 5, 

 p. 13. 



c Stockberger, W. W. Farmers Bulletin No. 304, U. S. Dept. Agriculture, 

 1907, pp. 19-26. 



<* Except when otherwise stated all analyses for arsenic were made in the 

 Bureau of Chemistry, United States Department of Agriculture. 



121— iv 



