RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



A handbook of colloid chemistry; the recognition of colloids, the theory of 

 colloids, and their general physicochemical properties. W. Ostwald, trans, 

 by M. II. Fischer (Philadelphia: P. Blakiston's Son rf Co.. 1919. pp. XVI+ 

 2$.'i, pi. 1. figs. 63). — This is the second English edition of this book, previously 

 rioted (E. S. R., 34. p. SOI). A few corrections in quotation and formulas have 

 boon made, and several paragraphs by E. Hatschek have been added on the 

 important advances in colloid chemistry, particularly those dealing with the 

 mechanical properties of colloids. 



Industrial and manufacturing chemistry. — I. Organic. G. Mw.tin kt m. 

 {T.nndon: Crosby Locktcood <( Son, 1918, -J. ed., rev. and ml., pp. .Y.Y-f?}'/. pis. 

 to. figs. 2J t 6). — In this revision of the hook previously noted (E. S. R., 84, p. 

 SOI) the various sections have been brought up 1o date. The new material 

 includes a short description of the cracking of oils, a discussion of the modern 

 nitrocellulose varnishes and dopes, and a description of modern methods of 

 bleaching linen yarns. A new section on the tobacco industry has been con- 

 tributed by S. E. Hodgkinson. 



Note on trypsin, and a new method of purifying enzyms. .1. T. Wood (Jour. 

 Koc. Chew. Indus.. 37 (1918). No. 83, pp. 313T-315T).—\ simple method of 

 purifying enzyms is reported, which consists essentially in BOaking pieces of 

 Swedish filter paper in the impure enzym solution and drying quickly in hot air. 

 When the paper thus treated is placed in water, the enzym is said to dissolve 

 quickly to a perfectly clear solution, while the colloidal mailer with which it is 

 associated adheres firmly to the paper. The liquid should be fdlered in from 

 IB to '_'() minutes. 



While the author does not consider this preparation to be a pure enzym. the 

 strength and purity are said to be greatly increased. 



Preparation of mediums: A new hydrogen-ion concentration method. L. .T. 

 Strong (Jour. Amer. Med. Assoc., 72 (1919). No. 6, p. ',13).— The adjustment of 

 mediums to the alkalinity of (tie human tissues is accomplished in the method 

 described by the use of phonolsulphoncphthaloin, 1 re. of which is added to 1 

 liter of the broth medium. About 5 re. of the medium i< poured into each of 

 two test tubes. To one tube a drop of any acid solution is added ami to the 

 other a drop of sodium hydroxid solution. To the remainder of the medium is 

 then added, drop by drop, acid or alkali until the color of about ."> cc poured 

 into a third test tube is between the color of the other two tubes, representing 

 a hydrogen ion concentration of pH=7. r >. 



The following advantages of this method are pointed out : No standard solu- 

 tion is used. Any tube that changes reaction can be told at a glance and 

 discarded before inoculating. Growth <>f all organisms is more rapid and lux- 

 uriant, always producing a color change. Much time is saved in the preparation 



of the medium. 



Pressed yeast and yeast extract in the preparation of media, P. [ORKBT 

 (Dnil. Med. WchflSChr., .',', (1918), An. 7. p. 1S6).— It is stated that dried yeasl 

 40S 



