CHEMISTRY. 225 



reached that the amid nitrogen was derived from two portions of the proteid 

 molecule and that the estimation of the quantities from. the different sources would 

 be of value. The author concluded further that melanin, at least the major portion, 

 was not formed at the expense of the easily cleaved nitrogen (amid nitrogen). 

 The distribution of nitrogen in ichthin and chitin was also studied. 



Concerning the estimation of albumen and some other nitrogenous con- 

 stituents of plants, N. Nedokutschajew ( Landw. Vers. Stat, 58 I 1903), Nos. 3-4, 

 pp. 275-280). — The analytical data reported led the author to conclude that the 

 unripe and ripe wheat grain contained proteids soluble in water, which are 

 thoroughly coagulated only when warmed under a pressure of 1.5 atmospheres. 

 When this was done no cleavage was noted which could affect analytical results. 



In addition to the true proteids the wheat contained albumoses precipitated from 

 a solution by saturation with zinc sulphate. Estimating proteids by heating to 

 112° ('. and precipitating albumoses with zinc sulphate gives somewhat higher results 

 than the Stutzer method. The grain in all stages of growth also contains an appre- 

 ciable quantity of nitrogen in compounds which are precipitated with phosphotung- 

 stic acid. A small amount of xanthin bases is also precipitated. 



The results of hot li quantitative and qualitative analyses warrant the conclusion, 

 in the author's opinion, that the unripe grain contains a complicated mixture of 

 crystallizable nutritious bodies. The diminution of these bodies as the grain ripens 

 indicates that they play an important role in the formation of reserve proteids. 



Volumetric determination of humus in soils by means of potassium per- 

 manganate, Ishcherekov (Zhur. Opuitn. Agron. [./our. Expt. Landiu.~\, 5 (1904), 

 No. 1, pp. 55-67). — The author criticises the methods at present in use as either too 

 complicated or inaccurate. The method proposed by him is as follows: 



After the soil is well pulverized in an agate mortar a sample weighing 0.5 to 0.1 

 gm., according to the richness of the soil in humus, is placed in a flask of 250 to 300 

 cc. capacity; into the flask a standard solution of potassium permanganate (y 1 ^ or £ 

 normal) is next introduced in considerable excess, from 2 to 2\ times as much as is 

 necessary for the complete oxidation of the humus content (0.01 gm. of humus 

 requires 9.72 cm. of \ normal potassium permanganate solution). Then 2 to 4 cc. of 

 sulphuric acid are added, i. e., somewhat more than is necessary for the reaction. 

 An amount of water equal to that of the potassium permanganate solution is also 

 added to replace the water evaporated in the subsequent boiling. The flask is 

 heated in an inclined position, bringing the contents to gentle boiling, which is 

 maintained for 40 to 50 minutes. Then titrate with oxalic acid. 



On the addition of the latter the characteristic color of the permanganate solution 

 disappears first and then the brown oxid of manganese, but the black manganese 

 peroxid sometimes dissolves with great .difficulty. In that case an excess of oxalic 

 acid is added, the liquid again brought to boiling, and the solution titrated back with 

 potassium permanganate. 



Assuming that all the oxygen given off by the potassium permanganate is used 

 up for the oxidation of the humus it is easy to calculate the amount of carbon dioxid 

 formed, from that the carbon of the humus, and then the humus itself. 



The method was tested with satisfactory results (which are reported) on a variety 

 of soils. The author in a number of cases collected the carbon dioxid formed in the 

 oxidation by potassium permanganate and calculated therefrom the humus and 

 obtained values which did not differ much from those given in the analyses. — 



P. FIREMAN". 



Determination of humus by the chromic method, A. N. Sabanin (Zhur. 

 Opuitn. Agron. [Jour. Expt. Landw.], 4 (1903), No. 5, pp. 573-594).— The author gives 

 the results of parallel determinations of humus in 126 soils by the chromic method 

 as carried out in the agricultural laboratory of the Moscow University, and by the 



9071— No. 3—04 2 



