RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICTJLTTTRAL CHEMISTRY— AGROTECHNY. 



The physics and chemistry of colloids, E. Hatschek (Chem. World, 1 

 (1912), Nos. 1, pp. 22, 23, fig. 1; 2, pp. 5J,-56; 3, pp. 90-92; 4, PP- 135-137; 5, pp. 

 no, 171; 6, pp. 208, 209; 7, pp. 243, 2U; 8, pp. 283, 284; 9, pp. 313, 314, figs. 2; 

 10, pp. 346-348, fig. 1; ll, pp. 391. 392, fig. 1; 12, PV- ^27, 428).— A detailed ex- 

 position of the physics and chemistry of the colloids. 



Modifications in the properties of the proteins of gliadin, A. J. J. Vande- 

 VELDE {Ahs. in Bui. Soc. Chim. Belg., 26 (1912), No. 1, pp. 14, Jf5).— Continuing 

 previous work (E. S. R., 27. p. 107), it is shown that if mixtures of wheat flour 

 containing either sodium chlorid, sodium sulphate, magnesium sulphate, am- 

 monium sulphate, tartaric acid, citric acid, oxalic acid, or tannin are made, 

 the elasticity of the gliadin seems to be lost. This is probably due to the 

 transformation of the gliadin into a nonelastic protein. 



In a dry mixture of wheat flour and casein the amount of gliadin that may 

 be extracted by kneading remains constant even after 1 month. 



If to the mixture water is added, the gliadin constantly increases, providing 

 the mixture is allowed to stand 24 hours before kneading. The same effect, 

 but in a less accentuated form, is produced when Witte peptone or egg white 

 is added to the flour. 



With the usual methods for gliadin in which alcohol is used, more gliadin 

 is obtained when salt is present in the flour. Flour deprived of its water in 

 a vacuum desiccator shows a constant amount of gliadin. 



Pectins of aucuba and sweet orang'e, V. Harlay (Jour. Pharm. et Chim., 7 

 ser., 5 (1912), No. 7, pp. 344-347; abs in Jour. Chem. Soc. [London], 102 (1912), 

 No. 595, II, p. 479). — The pectins isolated from aucuba fruits and sweet orange 

 fruit rinds are described. 



" The dry ground pulp of aucuba fruits was extracted with boiling water 

 and the extract precipitated with alcohol. The precipitate was purified by 

 (1) boiling with alcohol (90°) and (2) solution in water filtration, and re- 

 precipitation with alcohol containing hydrochloric acid. It was then a brown- 

 ish-white powder, containing 6.86 per cent water and 1.8 per cent ash, was 

 soluble in water, did not reduce Fehling's solution, and was precipitated from 

 its aqueous solution by limewater, baryta water, or copper sulphate solution. 

 It had [a]d -f 217.3° (corr.) in water, and by Tollens' method yielded mucic 

 acid, derived from galactan. 



" The white portion of sweet orange peel was freed from hesperidin by ex- 

 traction with alcohol, and the pectin was then isolated by the method described 

 above. It formed a white powder, giving an opalescent solution in water, which 

 was precipitated by the agents mentioned above. It had [a]d -f 176.6° (corr.) 

 in chloral hydrate solution, and on hydrolysis by dilute sulphuric acid gave 

 arablnose and with nitric acid gave mucic acid, the latter derived from 

 galactan." 

 608 



