SOILS fERTILIZERS. 817 



Apparently the most significant changes in the composition of the ash of the 

 plants showing the greatest Injury from the calcareous soils were an increase 

 in lime and a decrease in iron. The results, however, "do not warrant a de- 

 cisive conclusion that the diminished growth of all those plants which are af- 

 fected by the carbonate of lime is due to the same change in ash composition. 

 In fact, some quite marked changes in ash composition, as the decrease of 

 iron in bush beans, occurred without affecting the growth. And some depres- 

 sions in growth occurred, as [in case of] sugar cane, with practically no change 

 in ash composition." 



Sulphur in plant nutrition {Wisconsin Sta. Bui. 240 (191Jf), pp. 18, 19. fig. 

 1). — A brief note is given on pot experiments in which W. H. Peterson found 

 that where no sulphate had been applied the plants contained absolutely no 

 circulating sulphates. On the other hand, clover on soil which had been sup- 

 plied with gypsum contained an abundance of sulphates in the sap. "This 

 suggests that the determination of the amount of sulphates in growing plants 

 may be of value in showing whether or not a crop on a given soil is being 

 limited in growth by a scarcity of sulphates." 



In a study of the form and distribution of sulphur iu crops it was found 

 that such plants as June grass and red clover contained volatile sulphur com- 

 pounds, as is known to be the case with plants of the mustard family. 



Forms of sulphur in plant materials and their variation with the soil 

 supply, W. H. Peterson {Jour. Amer. Chem. 80c., 36 {1914), No. 6, pp. 1290- 

 1300; ahs. in Jour. Chem. Hoc. [Londmi^, 106 {1911,), No. 621, I, p. 9U).—Thls 

 is a more complete account of investigations briefly noted above. It reports 

 in detail the results of determinations of volatile sulphur, sulphates, soluble 

 nonoxidized sulphur, and insoluble nonoxidized sulphur in ruta-bagu'?, cabbage, 

 sugar beet, alfalfa, rape, radishes, clover, June grass, milk, oats, and wheat. 



The method used in determining the volatile sulphur in plants was in brief 

 as follows : Dry the material at 95 to 100° C. in a tube through which purified 

 air is drawn ; lead the gases over heated copper oxid and into an absorption 

 bottle containing glass beads and a concentrated solution of pota.ssium hy- 

 droxid ; when this operation is completed boil the copper oxid in water to dis- 

 solve the copper sulphate formed ; combine the solution in the absorption 

 bottle w'ith the washings from the copper oxid and concentrate the mixture 

 on the water bath ; cool and carefully neutralize with hydrochloric acid ; pour 

 the neutral solution slowly into bromin water; heat the oxidized sulphates; 

 and precipitate the resulting sulphates with barium chlorid. 



It was found that when only small quantities of sulphur were present In the 

 material it was all fixed as copper sulphate. In case of ruta-bagas and cabbage 

 the volatile sulphur amounted to about 10 per cent of the total sulphur. In 

 case of radishes and clover grown in the greenhouse, the amount present de- 

 pended upon the supply of sulphates in the soil, being four times as great with 

 an abundant supply of sulphates in the soil as without. A considerable pro- 

 portion (10 to 20 per cent) of the volatile sulphur in ruta-bagas was lost on 

 drying the green material in the steam oven. 



" Volatile sulphur was obtained from red clover, alfalfa, June grass, and 

 sugar beet tops not known to contain any bodies yielding such compounds. The 

 volatile sulphur in milk was also determined. The nature of this compound 

 is not known. In I'uta-bagas it is evidently of a sulphid form, as silver sulphid 

 is obtained when silver nitrate is added to the distillate from ruta-bagas. 



"The sulphates in the field samples examined varied from 10 to 50 per cent. 

 Where large quantities of sulphates were added to the soil, there was a cor- 

 responding increase of sulphates in the plant tissue. Rape, radishes, and clover 



