AGRICULTURAL CHEMISTRY AGROTECHNY. 505 



of Kjeldahl's method, wliicli consists of decomposing^ tlie mixture with fuming 

 and concentrated sulphuric acid and 1 drop of mercurj'. The error with diy 

 gases was on an average 0.75 per cent. 



The advantages of theWilfarth method over the Kjeldahl and phenol-sulphuric 

 acid methods are shown. 



A micro-Kjeldahl apparatus, M. Morse (Abs. in Biochem. Bui., 2 (1013)^ 

 No. 7, pp. 457, 4^8, pi. 1). — This is a combination of the apparatus designed by 

 Fritz Pregl for determining nitrogen in small quantities of material and the 

 fume absorber devised by Folin and Denis noted below. The apparatus is 

 regarded as equally serviceable with that devised by Sy (E. S. R., 28. p. 311). 



An apparatus for the absorption of fumes, O. Folin and \V. Dknis (Jour. 

 Biol. Chcm., 11 (1912), No. 5, pp. 50S-505, figs. 2). — An inexpensive apparatus 

 for this purjwse is described and illustrated. 



A modification of a method for examining fermentation gases, W. 

 Friebeb iCentbl. Bakt. [etc.], 2. AM., 36 {1913), No. 19-25, pp. Jf38-J,JfS, fig. 

 1). — What is claimed to be an improvement on Burri and Diiggeli's apparatus 

 and method "- is described. 



The volumetric determination of manganese in rock, slags, ores, and 

 spiegels, F. J. Metzger and L. E. Marks (Jour. Indus, and Engin. Chcm., 

 5 (1913), No. 2, pp. 12o, 126). — This is an application of a method previously 

 noted ( E. S. R., 24, p. 211 ) to the substances stated above. 



Importance of the error of analysis in questions relating to the nitrogen 

 economy of arable soils, T. Pfeiffer and E, Blanck (Landic. Vers. Stat., 78 

 {1912), No. 5-6, pp. 367^74; ahs. in Jour. Chem. Soc. [London], 104 (1913), 

 No. 604, I, p- 238). — "A final attempt was made to obtain a satisfactory nitrogen 

 balance with the experimental soils at Breslau. Six plats (9 square meters 

 each) were selected, which had given similar amounts of crops during 2 years, 

 and from each plat 5 samples of soil were taken. Ten or 12 nitrogen estima- 

 tions were made with each sample. The experimental error was found to be 

 ±0.00086, which would correspond with 25.8 kg. of nitrogen per hectare to a 

 depth of 25 cm. if the weight of the soil is taken as 3,000,000 kg., or 32.2 kg. 

 if the total weight of the soil is taken as 3,750,000 kg. As this number has to 

 be multiplied by 3, it would only be possible to show a difference exceeding 

 77.4, or 96.6 kg. of nitrogen per hectare. With fewer samples or analyses the 

 error would, of course, be greater. It must also be borne in mind that the ni- 

 trogen of crops is not all derived from the surface soil, but from the subsoil as 

 well." 



Note on the volatility of sulphuric acid when used in vacuum drying, 

 H. C. Gore {Jour. Bwl. Chcm., 15 {1913), No. 2, pp. 259-261, fig. i).— In the 

 course of some experiments in drying in high vacuum it was noted that sul- 

 phuric acid, when used as a desiccant, volatilizes, and when organic substances 

 such as flour are dried, they become darkened in color. In order to determine 

 the extent to which the acid volatizes, a Ilempel desiccator was charged with 

 7 Petri dishes, placed one above the other, and containing potassium hydroxid, 

 which was then exposed to the action of sulphuric acid for a period of 237 

 days at room temperature and at a vacuum somewhat less than 1 mm. The 

 amount of sulphuric acid collected in dish No. 1 was 0.2133, in No. 2, 0.044. in 

 No. 3, 0.0169, in No. 4, 0.0061, In No. 5, 0.0072, in No. 6, 0.0026, and in No. 7, 

 0.0029 gm., or a total of 0.293 gm. 



It is stated that lime may be successfully substituted for sulphuric acid. 



Direct determination of moisture in foods and miscellaneous materials 

 by distillation, F. Michel (Chcm. Ztg., 37 (1913). No. 35, pp. 353-355, figs. 4). — 



« Centbl. Bakt. [etc.], 1. Abt., Orig., 49 (1909), No. 2, pp. 145-174. 



