THE PRESENCE OF ARSENIC IN HOPS. 3 
samples were collected just before the crop was picked and were 
dried carefully in the open air, thus avoiding any possible chance of 
contamination from the sulphur. For comparison with the field 
samples thus prepared, samples of the hops from these fields, as well 
as samples of the sulphur used to bleach them, were taken at the kilns. 
Samples of kiln-dried hops and, when possible, samples of the sulphur 
used in bleaching them, were also secured from several widely sepa- 
rated localities. The soils on which these hops were produced varied 
from the alluvial sandy loam along the river to the clay loam of the 
uplands and represented practically all the soil types ordinarily 
used for the production of hops. 
Some samples of Fuggle, an early variety, also were collected for 
comparison as to arsenic content with the later variety known as 
Cluster or English Cluster. 
ANALYSIS OF MATERIALS. 
Arsenic was determined by the modified Gutzeit method, following 
in general the procedure outlined by C. K,. Smith. 1 A discussion of 
the method and of the reasons for adopting the exact details followed 
in this work will be published elsewhere. 2 The hops were treated with 
nitric and sulphuric acids to destroy organic matter. The sulphur 
was .treated with bromin 3 and the arsenic separated from the sul- 
phur bromid by extraction with bromin water. In all cases arsenic 
was precipitated as ammonium magnesium arsenate by adding mi- 
crocosmic salt, magnesia mixture, and ammonia. The precipitate of 
phosphate and arsenate was dissolved in sulphuric or hydrochloric 
acid, the arsenic reduced by stannous chlorid, and arsin generated 
by the use of zinc. The arsin was allowed to pass over a strip of 
paper containing mercuric bromid, making a brown stain, the length 
of which depended upon the quantity of arsenic in the sample. 
When large quantities of arsenic were present the arsin was passed 
into a solution of mercuric chlorid; the precipitated mercurous 
chlorid was filtered on ignited asbestos in a Gooch crucible, dried, and 
weighed. 
RESULTS OF ANALYSES. 
The results of the analyses of the field samples, dried in the sun 
without contact with sulphur fumes, are given in Table I. Although 
these samples came from widely separated yards and represented two 
varieties of hops, little difference is shown in their arsenic content, 
which is uniformly small. The analysis of samples 176, 201, and 202, 
i Smith, C. R. The determination of arsenic. U.S. Dept. Agr., Bur. Chem. Cir. 102, 12 p., 2 fig. 1912. 
2 Collins, W. D. C. R. Smith's method for the determination of arsenic (with special reference to the 
determination of arsenic in hops and in sulphur). Presented at the meeting of the Assoc. Off. Agr. 
Chem., Nov. 20-22, 1916. (To be published in Jour. Assoc. Off. Agr. Chem.) 
3 Smith, W. Estimation of selenium in sulfur. In Jour. Indus, and Engin. Chem., v. 7, no. 10, p. 849- 
S50. 1915. 
