SOURCES OF ARSENIC IN DRIED HOPS. 45 



of the same lot in which all the hops were grown and dried under 

 practically the same conditions, and also in samples drawn from dif- 

 ferent portions of one and the same bale. 



This apparent contradiction may be explained on the assumption 

 that the arsenic volatilized by the burning of the sulphur is deposited 

 on the layers of hops next the floor of the kiln while the upper layers 

 remain practically free. To test this theory, a series of experiments 

 was made with a small kiln in which different lots of hops were sepa- 

 rately exposed to the fumes of equal amounts of the different grades 

 of sulphur, after which samples were carefully taken from the top 

 and bottom layers before the hops were removed. The experiment 

 was repeated with double the quantity of each grade of sulphur used 

 before. For comparison, a certain quantity of arsenious oxid was 

 added to the sulphur, with which a final lot was treated. 



The preliminary results of these experiments fully support the 

 theory that arsenic may be transferred from sulphur to hops and 

 unequally distributed therein. The analysis of the samples shows 

 in practically every case a very appreciable difference between the 

 amounts of arsenic deposited in the upper and lower layers of the 

 hops. The evidence further indicates that the greater portion of the 

 arsenic is deposited in the bottom layer. The variation in the results 

 obtained with the different grades of sulphur was less than was an- 

 ticipated, since each grade apparently increased materially the arsenic 

 content of the hops. 



Although each test was repeated, using double the amount of sul- 

 phur, the relative proportion of arsenic present was not constant. 

 However, the results indicate that a larger arsenic content may be 

 expected when the proportion of sulphur used is increased. 



The samples from the last experiment, in which arsenious oxid (the 

 white arsenic of commerce) was added to the sulphur, contained rela- 

 tively large quantities of arsenic, twelve times as much being found 

 in the hops of the bottom layer as in those of the top layer. 



CONCLUSIONS. 



From the foregoing experiments the following conclusions are 

 drawn : 



(1) Traces of arsenic may occasionally be found in dried hops 

 irrespective of their geographical origin. 



(2) If available arsenic is present in the soil it may be taken up 

 by the hop plant under favorable conditions. 



(3) Except in rare cases the amount of arsenic derived from the 

 soil by the hop plant is probably smaller than 0.01 grain per pound 

 of dry hops, which is the smallest amount regarded as deleterious by 

 the Royal Commission on Arsenical Poisoning in England. 



121— IV 



