CHEMISTRY. 1049 



roots. It was assumed that the solution constantly bathing the roots in its flow 

 absorbed all the carbon dioxid secreted by them. The carbon dioxid was deter- 

 mined every third day, separately for the day ( 10 hours) and the night ( 14 hours) . It 

 was determined either by direct weighing after absorption in a potash bulb or by 

 Pettenkofer's method (absorption by standard caustic soda solution, precipitation of 

 the carbon dioxid by barium chlorid, and titrating back). Twenty-six estimations 

 for day and 25 for night periods were made during the 75 days of the growth of the 

 mustard. The plant developed luxuriantly and was in full bloom toward the end of 

 the experiment, when it reached a height of 1 meter. 



The data obtained show that the amounts of carbon dioxid set free during the day 

 and the night periods were nearly equal, that they gradually increased, though with 

 considerable fluctuations, to the last days of the experiment, and that the largest 

 amount of carbon dioxid secreted in one day was 0.335 gm. and in one night 0.275 gm. 

 The mean amount of carbon dioxid liberated in a day was 0.145 gm., and in a night 

 0. 152 gm. During the entire period of the experiment the mustard secreted 22.437 gm. 

 of carbon dioxid, the amount in 24 hours during the time of its most luxuriant growth 

 having been more than 0.5 gm. 



Having shown that the roots of plants secrete considerable quantities of carbon 

 dioxid in the course of their development, the author concludes that this carbon 

 dioxid may in some cases play an essential part in rendering assimilable the insolu- 

 ble plant food of the soil. In the experiment here described the amount of carbon 

 dioxid set free by the roots was about twenty times greater than would have been 

 required to render soluble all the phosphoric acid assimilated by the plants if it were 

 supplied in an insoluble form. This amount of carbon dioxid would have been suffi- 

 cient to render soluble all the elements of the ash of the entire plants if it were neces- 

 sary to assimilate these elements from insoluble substances. — p. fireman. 



Acidity of plant roots, C. Montanari (Staz. Sper. Agr. Hal., 37 (1904), j)p. 806- 

 809; abs. in Jour. Chem. Soc. [London], 88 (1905), No. 509, II, p. 191).— The colora- 

 tion observed by Kohn" is stated to be only apparent since similar results are obtained 

 without roots. The reddening of litmus paper in contact with sugar-beet roots is 

 attributed to the diffusion of the root acid. 



The preparation of standard solutions of sulphuric acid, B. North and W. 

 Blakey (Jour. Soc. Chem. hid., 24 (1905), No. 8, pp. 395-397). —Directions are given 

 for purifying and using sodium bicarbonate for this purpose. 



The determination of alkalis in silicates by Smith's method, B. M. Mar- 

 gosches (Chem. Ztg., 29 (1905), No. 29, p. 385). 



A crucible cooler for the determination of alkalis according to L. Smith, 

 R. L. Steinlex (Chem. Ztg., 29 (1905), No. 27, pp. 364, 365, fig. 1). 



Methods for the examination of maple products, J. Hortvet ( U. S. Dept. 

 Agr., Bureau of Chemistry Circ. 23, pp. S, fig. 1). — This is summarized from an article 

 by the author previously noted (E. S. R., 16, p. 846). In this form these directions 

 were intended primarily for the use of chemists of the Association of Official Agri- 

 cultural Chemists collaborating in testing methods for maple products. 



Potassium oxalate as a lead precipitant in sugar analysis, H. E. Sawyer 

 (Jour. Amer. Chem. Soc, 26 (1904), No. 12, pp. 1631-1635).— The author has substi- 

 tuted with satisfactory results neutral potassium oxalate for the sodium carbonate 

 required by the official method of the Association of Official Agricultural Chemists 

 for precipitating the excess of lead subacetate previous to the examination with 

 Fehling's solution. 



Cinnamon starch, A. Beythien, H. Hempel, and P. Bohrisch (Ber. Untersuch. 

 Dresden, 1903, p. 15; abs. in Ztschr. Untersuch. Nahr. u. GenussmtL, 9 (1905), No. 4, 

 p. 231). — Studies of the starch found in cinnamon are reported. Like other investi- 



«Landw. Vers. Stat., 52 (1899), pp. 315-326. 

 30858— No. 11—05 2 



