2 BULLETIN" 568, U. S. DEPARTMENT OF AGRICULTURE. 



occasionally found in American hops, and hop growers and handlers 

 were urged to avoid the use of sulphur which could contaminate the 

 hops in the process of drying and curing. Following this publication 

 some hop growers made an effort to secure arsenic-free sulphur, but 

 most of the growers on the Pacific coast continued to use impure 

 sulphur, with the result that each year hops contaminated with 

 arsenic have found their way into foreign markets. In the hops 

 produced in the crop year 1914 the quantity of arsenic present was in 

 many cases so much larger than usual that some English consumers 

 brought the matter informally to the attention of the Bureau of 

 Plant Industry and expressed the hope that American hop growers 

 could be made to realize the seriousness of the situation from the 

 standpoint of the foreign purchaser. 



From an inquiry made among the hop growers of the Pacific coast 

 it appeared that the sulphur in common use for bleaching hops was 

 generally regarded either as free from arsenic or as containing this 

 element in quantities so small that no injury would result from 

 its use. The soil, commercial fertilizers, and materials used in 

 spraying, rather than the sulphur, were all suggeste-d as prob- 

 able sources of the arsenic in hops, but on account of the prevailing 

 uncertainty as to its real source little progress apparently was made 

 in the production of hops of a quality more acceptable to the foreign 

 trade. The reliability of the methods used for the determination of 

 small quantities of arsenic in hops and similar materials was questioned 

 "by some who had given careful consideration to the subject. There- 

 fore, the Bureau of Plant Industry and the Bureau of Chemistry 

 undertook a joint investigation in order to establish definitely the 

 source of the contamination of the hops. The field investigation and 

 the collection of samples were made by the representative of the 

 Bureau of Plant Industry, while the study of methods of analysis and 

 the analyses of the samples collected were made in the Bureau of 

 •Chemistry. 



COLLECTION OF MATERIALS FOR EXAMINATION. 



The hop-producing sections of Oregon were visited during the hop 

 harvest of 1915, and a carefully selected series of samples of both 

 hops and sulphur was obtained. Definite information was in hand 

 regarding the origin of certain bales of hops of the crop of 1914 which 

 had been rejected by English purchasers, and it was therefore possi- 

 ble to locate the particular fields on which the hops in many of these 

 bales were produced. It was possible also in some cases to locate 

 and examine the kilns in which some of the rejected hops were dried 

 and to secure samples of the sulphur used in their preparation. 



Composite samples of hops from several fields were secured by 

 taking a few hops from each of a number of vines in a field. These 



