1917] AGRICULTURAL CHEMISTRY AGROTECHNT. 503 



2. ser., 8 (li)16). No. 7-9, pp. S J 9-352). —From the results of the study it is con- 

 cluded that the different species of microorganisms can be differentiated colori- 

 nietrically by means of the paracresol-tyrosinase reaction. Most of the amino 

 acids give with equimolecular proportions of paracresol and tyrosinase a red 

 color, which, in the presence of an excess of the amino acid, more or less 

 rapidly turns blue. Glyeyltyrosiu and a great number of other polypeptids 

 xeact with less intensity. The rapidity and intensity of the reaction depends 

 upon the quantity of the culture present and also upon the age of the culture. 

 These functions vary with the different species. The nature of the culture 

 medium was also found to influence the reaction. A parallelism between the 

 color and the amount of gelatin liquefied was noted. Light did not affect the 

 reaction. Low temperatures, however, greatly retarded the development of the 

 color. The reaction was found to be vahiable in detecting indol. especially 

 when present only in very small amounts with skatol. 



The relation of microorganisms to the ripening of cheese is noted. 



The data are submitted in detail and discussed. 



A course in food analysis. A. L. Winton {New York: John Wiley tC Sons, 

 Itw., 1917, pp. IX +252, figs. 107). — This volume considers dairy products, meat 

 and fish, natural vegetable foods and mill products, microscopic examination 

 of vegetable foods, saccharine products, fats and oils, fruits, fruit products, 

 liquors and vinegars, flavoring extracts, coffee, tea, and cocoa. Calculation 

 tables and a list of apparatus, reagents, and practice material are appended. 



The book is intended to give an introductory course in the subject prior to 

 the use of more extensive works or to meet the needs of the general student. 



A simple device for evaporating solutions to a definite volume, G. P. 

 Pi.AisANcE and N. C Pekviek (Jour. Amer. Chem. Soc, 39 (1917), No. 6, pp. 

 1238-12^0, figs. 3). — An easily assembled apparatus and its manipulation are 

 de.scribed in detail. 



An evaporating bath of sea sand heated by steani, P. P. Peterson (Jour. 

 Indus, and Engin. Chem., 9 (1917), No. 7, p. 686, figs. 2). — An apparatus in 

 which the sand bath is heated by coils of pipe through which superheated steam 

 is passed and » ontrolled by a suitable steam trap is described. 



Handling laboratory solutions by suction, C L. Beals (Jour. Indus, and 

 Engin. Chem.. 9 (1917), No. 6, p. 603, fig. i).— The author, at the Massachusetts 

 Experiment Station, describes an apparatus and its construction for obtaining 

 solutions from large containers. The apparatus was successfully applied to 

 measuring dilute acid and alkali solutions used in fiber determinations. 



A note on an automatic suction attachment for an ordinary pipette, J. P. 

 ScHKOEDER (Jour. ludus. and Engin. Chem., 9 (1917), No. 7, pp. 687, 688, figs. S). — 

 An apparatus which consists essentially of the attachment of a stopcock to an 

 ordinary pipette, or for automatic measurement a Gooch crucible filter tube 

 and a stopcock, is described. 



A simple device for the automatic and intermittent washing of precipi- 

 tates, E. C. Latheop (Jour. Indus, and Engin. Chem., 9 (1917), No. 5, pp. 527, 

 528, fig. 1). — An apparatus which has yielded excellent results and its manipu- 

 lation are desi^ribed in detail. 



An improved form of a fumeless digestion apparatus, J. S. McHaegue 

 (Jour. Indus, and Engin. Chem., 9 (1917), No. 7, pp. 686, 687, fig. i).— The 

 author, at the Kentucky Experiment Station, describes an enlarged and modified 

 Sy fumeless nitrogen digestion apparatus (E. S. R., 28, p. 311). The apparatus 

 Is indicated as yielding excellent results. 



An apparatus for the purification of mercury, H. E. Patten and G. H. 

 Mains (Jour. Indus, and Engin. Chem., 9 (1917), No. 6, pp. 600-603, figs. 3).— 



