1919] AGRICULTURAL CHEMISTRY — AGROTECHNY. 115 



red color develops and spreads through the acid. This color is discharged by 

 a few drops of water but returns on the addition of more sulphuric add. 

 The tesl is said to be \*'ry delicate with most aldehydes and to be given 



also with the Substituted aldehydes such as chloral. The color varies slightly 

 with the aldehyde. Formaldehyde gives a purple-red, acetaldehyde a cherry- 

 red, and acrolein a rose-carmine color. 



The measurement of the acidity of bread, E. J. CoHN, P. II. CATHCABT, and 

 L. .1. Hendkbson {Jour. Biol. Chem., 86 {1918), No. S, i>i>. 581-586, fig. /).— A 

 simple method Cor determining the H-ion concentration of bread is described, 

 which consists essentially of applying lour drops of a 0.02 per cent solution of 

 methyl orange In 00 per cent alcohol to the freshly cut surface of the bread 

 near the center of the loaf. The color is observed after five minutes, and is 

 compared with a color chart or with that produced in a loaf of bread of known 

 acidity. Baking experiments upon dough of known but graduated acidities 

 have shown that the range from orange to red corresponds to initial values 

 of pll ranging from approximately 6 to 4.5. 



Determination of pectins in spices, T. von Fellenberg {Mitt. Lebensm. 

 Untersuch . u. Jim/., Schirciz. (Isndlttsamt., 7 (1916), No. 1-2, pp. 42-61). — A 

 method for the determination of pectins is described which consists essentially 

 in removing the methyl esters other than the pectins by extraction with ether 

 and distillation with steam. The pectins are then saponified with sodium 

 hydroxld, and the methyl alcohol is obtained by distillation from the acidified 

 solution. 



Tables are given of the methyl alcohol and pectin content of spices and of 

 materials used in their adulteration. 



The photographic examination of fresh and preserved eggs, G. A. Le Roy 

 {Compt. Haul. Acad. Sci. [Paris], 165 (1911), No. 25, pp. 1026-1028, fig. 1; 

 Ann. Falsi/., 11 (1918), No. 111-112, pp. 10-18, figs. 4; abs. in Chem. Abs., 12 

 (1918), No. 10, p. 1086). — The author describes the construction and operation 

 of an apparatus for photographing eggs in such a way that the size of the air 

 chamber may be accurately measured. 



Determination of caffein in coffee, E. Vautiek (Ann. Chim. Analyt., 28 

 (1918), No. 10, pp. 207-210).— The method consists in extracting 5 gin. of the 

 finely ground sample, to which 5 cc. of ammonium hydroxid has been added, 

 with ether for four hours in a Soxhlct apparatus. After removal of the ether by 

 distillation, the caffein is separated from the fat by treatment with boiling 

 water, and is then filtered, washed, and sublimed, and the sublimate heated in 

 an oven at 100 C. for about 20 minutes. 



A table is given showing the similarity in results obtained by this method 

 and by the chloroform extraction method with samples of ordinary and de- 

 caffeinated coffee. 



The testing of palm butter in the laboratory of the General Experimental 

 Station of the A. V. R. O. S., with some hints for the manufacture of palm 

 butter, F. C. van Heurn (Meded. Alg. Proefstat. Alg. Ver. Rubberplanters Oost- 

 kust Sumatra, Alg. Ser., No. 2 (1918), pp. 37). — An examination of various 

 methods for determining the analytical constants of palm butter is reported. 



For determining the moisture content, distillation with kerosene is considered 

 the best method if the moisture content is higher than 4 per cent, while if less 

 than 4 per cent heating at 105° C. for two hours is recommended. Kerosene is 

 considered preferable to alcohol as a solvent for the fat in the separation of in- 

 soluble impurities. In determining the acid number, it was found necessary to 

 use a very dilute solution of the fat in alcohol on account of the deep color 

 of the concentrated solution. The author states that it is possible to produce 



