504 EXPERIMENT STATION RECOBD. 



in a specially graduated cylinder. The cylinder is so graduated as to read per- 

 centages of calcium carbonate directly. In a series of comparison tests with a 

 more exact quantitative method for the determination of calcium carbonate 

 in limestone very close average agreement results was obtained. The apparatus 

 was standardized at 25° C. and 740 mm. pressure, and a correction table for 

 temperatures below and above 25" is given. "The apparatus possesses suffi- 

 cient accuracy and simplicity to meet all the necessary requirements involved 

 in testing a limestone proposed for agricultural use." 



Methods for the determination of carbon dioxid and a new form of absorp- 

 tion tower adapted to the titrimetric method, E. Trvog (Jour. Indus, and 

 Engin. Chem., 7 (1915), Ko. 12, pp. 1045-1049, fig. i).— The author discusses the 

 sources of error and precautions necessary in the gravimetric method and ab- 

 sorption in alljali hydroxids for the determination of carbon dioxid. A new 

 form of absorption tower, using barium hydroxid as the absorbing medium, is 

 described, and illustrated by a figure. Claims for the elimination of practically 

 all contamination of carbon dioxid from the air and a very good end point 

 in the titration are made. The newly proposed method has given good results 

 as used at the Wisconsin Station. 



The determination of iodin in the presence of organic matter, R. B. Kbaltss 

 (Jour. Biol. Chcm., 22 (1915), No. 1, pp. 151-157). — A coloriraetric method based 

 on the formation of palladous iodid in a .solution of iodids is described in detail. 

 The method eliminates the usual sources of error, viz, the addition of iodids, 

 idates, or halogens. The procedure is deemed especially applicable to the de- 

 termination of iodin in organic matter after fusion. Experimental data sub- 

 mitted indicate the accuracy of the method. 



The reaction of soil and measurements of hydrogen-ion concentration, 

 L. J. Gillespie (Jour. M'ash. Acad. Sci.. 6 (1916), No. 1. pp. 7-16, figs. 2).— The 

 author has devised procedures for the electrometric and colorimetric determina- 

 tion of the hydrogen-ion concentration in soil, to ascertain the intensity of soil 

 acidity. The hydrogen-ion exponents deterniine<i in 22 .soils ranged from 4.4 

 to 8.6, an exponent of 7 representing neutrality, a smaller one acidity, and a 

 larger one allcalinity. In all cases there was close agreement in results between 

 the electrometric and colorimetric methods. The apparatus and manipulation 

 are described in detail. 



The calculation of total salt content and of specific gra\nty in marine 

 waters, R. II. Tkt-e (Science, n. ser.. .',2 (1915). Xn. 1090, pp. 732-735. fig. 1). 



The Kjeldahl-Gunning-Amold method for nitrogen, J. M. Pickel (Jour. 

 Indus, and Engin. Chem., 7 (1915), No. 4. p. 357). — From experimental data sub- 

 mitted tlie author regards 30 minutes' vigorous boiling, from start to finish, 

 as sufficient for the determination of the organic nitrogen by the Kjeldahl- 

 Gunning-Arnold method, using a 0.7-gm. sample. 



A note upon the Kjeldahl method for nitrogen determination, P. L. Blu- 

 MENTHAL and G. P. PLAISANCE (Jovv. Indus. and Engin. Chem., 7 (1915), No. 

 12, pp. 1044. 1045). — While engaged in analyzing the carcasses of newborn pigs 

 at the Iowa Station, some difficulty was experienced in obtaining concordant 

 results in the nitrogen determinations. After conducting a series of analyses 

 under varying conditions it was found that the Kjeldahl-Gunning-Arnold and 

 the Gunning-Copper sulphate digestions cleared more quiclvly than those of 

 the other methods tested. Experimental data sulmiitted indicate that 30 min- 

 utes' total heating, as recommended by Pickel (see above), is not sufficient 

 to fix all the nitrogen in the protein material. ■ Heating for a definite length of 

 time after clearing of the solution was found a more satisfactory proco<lure 

 than a definite length of time of total heating. An explanation of tlie forma- 



