710 EXPEEIMENT STATION RECORD. 



open storage appears to be the least effective in retarding the formation of 

 esters. Nonsulphuring and open storage appears to be the most effective in re- 

 tarding the formation of esters. 



"The saponification value in general increased in all the samples of hops. 

 The imsulphured hops showed the least change, and of these, the ones held in 

 open storage were the least affected. 



"The iodin value in general increased in all the samples. It was most pro- 

 nounced in the second year of storage and in the third j^ear was uniform in all 

 the samples. Sulphuring in combination with open storage appears to cause 

 a uniform rate of increase in the iodin value from year to year. The sulphured 

 hops in open storage showed the least variation in changes in the chemical values 

 of the soft resins. 



" During the period of storage, at least some of the components of the soft 

 resins underwent rearrangement. This rearrangement was most marljed dur- 

 ing the first year, after which it decreased to such an extent that thereafter 

 comparable values for the chemical constants were readily obtained." 



The amount of arsenic in solution when lead arsenate is added to different 

 spray solutions, W. B. Ellett and J. T. Grissom {yirginia Sta. Tech. Bui. 8 

 (1915), pp. 160-164; lipts. 1913-14, pp. 160-164).— '' Sodinm and potassium 

 sulphids dissolve more arsenic when mixed with lead arsenate than the com- 

 mercial lime and barium sulphur spray solutions. When arsenate of lead is 

 added to either the sunnner strength of sodium sulphur or potassium sulphur, a 

 large percentage of arsenic goes into solution. Barium chlorid retards the solu- 

 bility of the arsenic when added to sodium and potassium sulphids. 



When lead arsenate is added to the different sulphur spray solutions, the 

 amount of arsenic in solution is increased. This accounts for the burning effect 

 when used together as a spray. ... If mixtures with arsenic are desired for 

 spraying, lead arsenate is less harmful than Paris green, 



" With calcium and barium the arsenic is less soluble than with sodium and 

 potassium. . . . Barium arsenate, when used with the different sulphur sprays, 

 indicates that slight burning would take place with lime and barium sulphur, 

 and that the amount of arsenic in solution is less than \vhen used with water. 

 With sodium and potassium sulphids this substance would be harmful." 



Two rapid methods for determining potassium, F. Ckotogino (Kali, 8 

 (1914), pp. 332-334; «^s- 'i'^ Ztschi: Angeic. Chem., 27 (1914), No. 99, Referatenteil, 

 p. 697). — The first method is approximate and consists of adding dropwise 

 sodium perchlorate to the potassium cidorid solution until no further precipita- 

 tion is obtained. 



A more exact method is as follows: To 5 cc. of the solution (3.395 gm. in 50 

 (cc.) add 4 cc. sodium perclilorate solution (2,100 gm. in 2,110 cc. of water), 

 rotate, and filter through a weighed filter paper with the aid of the air pump ; 

 then wash with alcohol, dry the filter paper and contents at from 135 to 140° 

 C, and weigh. The method requires 15 minutes to carry out. The variation in 

 the results of 35 determinations was 0.23 per cent. 



Greeff's method for the volumetric estimation of fluorin, I. Bellucci (Ann. 

 Chem. Appl. [Rome], 1 (1914), No. 9-10, pp. 44I-446; ahs. in Jour. Chem. Soc. 

 [London], 106 (1914), No. 621, II, p. 57^).— Tests were made with varying 

 amounts of sodium fluorid in order to ascertain the accuracy and limits of 

 applicability of the method.*^ 



" The conditions given by this method yield accurate results only when the 

 amount of alkali fluorid does not differ greatly from 0.2 gm. ; thus 0.05, 0.04, 

 and 0.02 gm. taken gave, respectively, 0.0449, 0.0336, and 0.0078 gm. found. With 



•Ber. Deut. Chem. Gesell., 46 (1918), No. 12, pp. 2511-2513. 



