RECENT WORK IX AGRICUETURAL SCIENCE. 



AGEICULTUEAL CHEMISTRY. 



The corrosion of iron, A. S. Clshmax ( ['. ,S'. Dcpt. Agr.. Office Puh. Roads 

 Bui. 30, pp. 35. pis. 7", figs. 3). — Some method of rendering the metal used for 

 culverts, fence wire, and otber purposes more resistant to corrosion would be 

 of immense importance to agriculture. In the search for this, knowledge of 

 the causes of corrosion is fundamental. The author discusses the carbonic-acid 

 theory, the peroxid theory, and the electrolytic theory of corrosion, with experi- 

 mental evidence against and in support of them. 



In his opinion the electrolytic theory most satisfactorily explains the 

 phenomenon of corrosion of iron. According to this theory rusting of iron 

 must take place with the establishment of positive and negative spots. At the 

 positive points iron will pass into solution and be oxidized to colloidal hydroxid 

 form, which will migrate toward the negative point. The electro-chemical 

 action was demonstrated by treating iron and steel with a specially prepared 

 reagent, containing phenolphthalein. which marks the hydroxyl ions by red 

 color at the negative points, and a trace of potassium ferricyanid. which marks' 

 the ferrous ions at the positive points by the formation of Turnbull's blue. 

 To prevent diffusion and preserve the effects produced the reagent was pre- 

 pared with gelatin, and the pieces of metal were embedded in the jelly. 



Two ways by which questions attendant uix)n rapid corrosion may be met 

 are suggested. One is by the manufacture of better metal, and the other by 

 the use of inhibitors and protective coverings. Laboratory tests with the latter 

 apparently indicate that chromic acid with its salts may, under certain circum- 

 stances, be used to inhibit extremely rapid corrosion by electrolysis. 



Report on colors: The solubility and extraction of colors and the color re- 

 actions of dyed fiber and of aqueous and sulphuric-acid solutions, H. M. 

 LooMis iU. S. Dcpt. Af/r.. Bur. Chem. Circ. 35, pp. 51). — The results are given 

 of tests with a large number of coloring matters, the data being of value espe- 

 cially in connection with studies of coloring materials in foodstuffs and meth- 

 ods for their detection. 



The heat of combustion of vegetable proteins, F. G. Benedict and T. B. 

 OsBORXE {.Jour. Biol. Chew.. 3 (1007). Xo. 2, pp. 119-133).— E\ementnry 

 analyses and determinations of the heat of combustion of a number of vege- 

 table proteins are reported. 



The smallest values. 5.358 and .5.3.59 calories per gram, were found respec- 

 tively with wheat globulin and with conglutin from yellow lupine, and the 

 highest value, 5.916 calories per gram, with hordein. In general, higher heats 

 of combustion were observed in the materials examined which, the authors 

 and with those having a lower oxygen content. Many irregularities in heat 

 of combustion were observed in the materials examined which, the authors 

 believe, are due to different proportions of the various amino acids which con- 



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