204 EXPERIMENT STATION EECOED. IVol. ^6 



necessary, however, the nitrites may be removed from a second portion of the 

 sample by boiling with acetic acid and the efCect of the organic matter deter- 

 mined by a blank titration. 



It is concluded that " nitrous nitrogen can be determined titrametrically 

 when care is tali:en to expel the air from the titration flask with some gas which 

 will not affect the determination." 



Notes on soil analysis, K. Gedkoits (Zhur. Opytn. Agron., 16 (1915), No. 1, 

 pp. 83-94 ) . — The determination of the loss in soils which do not contain carbon 

 dioxid, alkalis, and chlorids of metals by calcination at temperatures from 

 530 to 560° C. showed that within these limits the higher the temperature the 

 smaller was the loss. The same phenomenon was observed for soils in general. 



Determination of the loss by calcination for soils containing calcium car- 

 bonate and chlorids of metals showed during a period of one hour at the tem- 

 perature noted above the same results as calcination of soils not containing 

 these substances. If the soils contained magnesium carbonate in addition to the 

 above, the procedure could not be used on account of the decomposition of mag- 

 nesium carbonate. The determination is rendered still more difficult if in 

 addition to magnesium carbonate the soil contains considerable quantities of 

 chlorids, as the effect of high temperature on the latter will depend on their 

 composition and on the composition of the soil, containing possibly sodium, mag- 

 nesium, calcium, and other chlorids. Calcium and magnesium chlorids are not 

 volatilized on heating but may be decomposed to a greater or lesser extent, 

 especially magnesium chlorid, on account of the hydrolytic action of the water 

 in the soil. Sodium chlorid is volatilized entirely by heating over the flame of 

 a Teclu burner. 



It is indicated that the processes taking place in the soil during calcination 

 are not clearly understood. The temperature of heating should apparently be 

 from about 530 to 560°. 



Decomposition of a soil containing sulphates by means of hydrofluoric acid is 

 a very disagreeable operation on account of the necessity of evaporating the 

 excess of sulphuric acid, and experiments were made in which hydrochloric acid 

 was substituted for sulphuric acid. To 5 gm. of a fine black loam soil in a 

 platinum dish was added 25 cc. of fuming hydrofluoric acid (38 to 40 per cent), 

 and the mixture evaporated slowly to dryness on the water bath. To the dry 

 residue 15 cc. more of the acid was added and 25 cc, of hydrochloric acid 

 (specific gi'avity 1.19) and the mixture again slowly evaporated. The latter 

 process was repeated a second time, when complete decomposition of the 

 mineral substance was obtained. In order to remove the hydrofluoric acid com- 

 pletely the residue was treated four or five times with hydrochloric acid in a 

 boiling water bath, dried, transferred to a suitable container, heated with 

 hydrochloric acid, filtered through an ashless filter, and carefully washed with 

 hot water and a weak solution of hydrochloric acid. The filtered residue was 

 then treated with more hydrochloric acid and nitric acid, and the filtrate 

 was neutralized in the usual manner and found to contain aluminum, potassium, 

 phosphorus, and traces of calcium. 



The determination of the alkalinity and phosphoric acid content in the 

 ash of foodstuffs, I. M. Kolthoff (Chem. Weekbl., IS (1916), No. S3, pp. 910- 

 914). — The author briefly reviews the method described by Farnsteiner (E. S. 

 R., 18, p. 1107) and indicates some disadvantages in its use. 



For the determination of the alkalinity of the ash the following procedure is 

 described : From 0.2 to 0.3 gm. of ash are treated with hydrochloric acid as 

 in the method of Farnsteiner, filtered, and the filtrate neutralize<^i with tenth- 

 normal sodium hydroxid. A solution containing 0.25 gm. of neutral potassium 

 oxalate and a solution containing the same amount of sodium chlorid are then 



