CHEMISTRY. 417 



composition of the various feeds appearino; from time to time and their microscopic 

 examination was later considered. 



No changes of any importance were made in the methods of i4eed testing. 



Some consideration was given to an improved method of potash determination, a 

 paper on the subject being submitted by Scluilze. The Neubauer method (E. S. R., 

 12, p. 714) was assigned for further testing. 



The question of international atomic weights was discussed by Fresenius. 



The subject of the condition and needs of the agricultural experiment stations 

 was treated by Konig. Amung the questions submitted for the consideration of the 

 association were the overburdening of the stations by control work, so as to seriously 

 hamper their experimental studies; the deficiency and the training of alile assistants; 

 the desirability of closer cooperation with the Association of German Scientists and 

 Physicians; the improvement of the reports of the stations, and certain deficiencies 

 in experimental work and in the applications of the results. 



Proceedings of the committee on foods and feeding, of the Association of 

 Agricultural Experiment Stations in the German Empire {Landw.Ver. Stat., 

 56 {1901), No. 1, jxp. 81-94). — This committee, tpmposed of Messrs. Emmerling, 

 Kellner, Loges, Schulze, and Weigmann, met in Berlin, February 11, 1901. The 

 subjects considered were the preparation of food samples for analysis, the drawing 

 of samples, the microscopic examination of rape cake, molasses feeds, the addition 

 of phosphoric or sulphuric anhydrid in nitrogen determination, the tax on ether 

 used by the stations, and the microscopic examination of foods. 



The passing of all food materials for analysis through a millimeter sieve was made 

 obligatory. A few minor changes were made in methods of drawing samples. 

 With molasses feeds there were discussed the water content, the relative value of 

 the proteid and non-proteid nitrogen, and the quantitative estimation of total and of 

 invert sugar. A paper on the optical and gravimetric estimation of sugar in molas- 

 ses feeds was presented by Schulze. The report on the addition of phosphoric or 

 sulphuric anhydrid in nitrogen estimations was made by Kellner. Upon motion of 

 the referee the method was referred to the committee for further study in compari- 

 son with the Gunning method. 



A rapid method of determining carbonic acid in air, J. Haldane {Jour. Hyg. 

 [Canibrklge'], 1 {1901), No. 1, pp. 109-114, fig. 1). — This method involves the use of a 

 specially constructed apparatus, which is figured and described. A sample of the air 

 is drawn into a gas l)urette, driven backward and forward through a potash solu- 

 tion, and again measured after the absorption of the carbonic acid. The difference 

 between the 2 readings gives directly the number of volumes of car])onic acid per 

 10,000 in the sample of air. Trials show that the method is reliable to about 0.5 

 volume per 10,000, a degree of accuracy sufficient for most practical purposes. 



The advantages of the method are that the apparatus can be easily carried about, 

 an accurate result can be obtained in about 5 minutes, and no calculations are involved. 



On the determination of humus in cultivated soils, K. Bieler and K. Aso 

 {Bill. Col. Agr. Imp. Univ. Tokyo, 4 {1901), No. .^, 2>jt>. ^,?7-;?.^0).— This article reports 

 comparative tests of the accuracy of the determination of humus by means of (1) 

 elementary analysis, (2) Knop's method, (3) Snyder's extraction method (E. S. R., 

 5, p. 932; 6, p. 691), and (4) Aschman and Faber's volumetric method (E. S. R., 11, 

 p. 110). The results obtained indicate that the figures given by elementary analysis 

 are too high. The amount of hunuis yielded by the extraction method was only 71 

 per cent of that indicated by elementary analysis. The percentages of humus found 

 in the air-dry soil by the different methods w'ere as follows: P^lementary analysis 

 13.84 per cent, Knop's method 8.85 per cent, extraction method 9.79 per cent, volu- 

 metric method 6.95 per cent. The methods are to be further tested on different 

 kinds of soils. 



