AGRICULTURAL CHEMISTRY— AOBOTECHNY. 313 



chemical inake-ui) of the soil, the composition of the soil air. the temperature, 

 the time of ye;ir, and the animal and vegetable life contaiu«Hl therein. Methods 

 are briefly discussed under the headings of hygroscopically and mechanically 

 absorbed water in soil; water capacity; water vapor and oxygen in the soil 

 air; air capacity of the soil; whether the organic substance of the soil will 

 serve as a good source of carbon for heterotrophs ; the respiratory intensity 

 of soil bacteria, and the cleavage of organic substances in the soil; anaerobic 

 and aerobic respiration of bacteria iu the soil; nitrogen requirements of soil 

 micro-organisms; oxidation processes of nitrogenous substances in the soil; 

 putrefaction of nitrogenous organic substances by anaerobic organisms; ii 

 biochemical method for determining available phosphoric anhydrid and potassium 

 oxi<I in tlie soil; bacteriological soil examinaton; cellulose-destroyng power of 

 the soil ; detection of bacteria which decompose carbohydrates in the soil ; soil 

 catalase; and biological absorption of the soil. In some cases the interpreta- 

 tion of the results obtained on the basis of the above methods is described. 



A full account of the methods mentioned has been previously presented by 

 Abderhalden (K. S. 11., 27, p. 107). 



Estimation of total carbon in soils, M. E. Pozzi-Escot (Bui. Assoc. Chini. 

 Hucr. ct Distill., SO {lUIS), No. 10, pp. 618-621; abs. in Jour. Chem. Soc. 

 [London], 104 (1913), No. 609, II, p. 622).— In this method a quantity of soil 

 containing not more than 0.3 gm. of organic matter is mixed in a nickel boat 

 with 0.1 gm. of fused potassium bichromate and 1 gm. of lead chromate, and 

 the combuston conducted in the usual manner. 



It is necessary to employ a large excess of oxygen, but the rate at which this 

 gas is passed through the combustion tube must be slow. It is advisable to 

 pack the tube with copper oxid in the form of threads for a length of at least 

 350 mm. and the copper foil usually employed may be rei)laced by silvered 

 pumice. The carbon dioxid formed is absorbed in a suitable apparatus and 

 weighed. 



The author criticizes the method described recently by Gr§goire (E. S. R., 

 28, p. 708). 



Estimation of carbon and carbon dioxid. A. (Jr^goire, J. Hendkick. E. 

 Caupiaux, and E. Germain (Ann. Chini. Analijt., 18 (1913), No. 1, pp. 1-8, fig. 1; 

 obs!. in Jour. Chem. Soc. [London]. lOJf (1913). No. 605. II, p. 2//.?).— The 

 method proposed has been previously described (E. S. R., 28, p. 708). 



The application of Folin's method for the determination of ammonia to 

 fertilizers, O. Foun and A. W. Bosworth (Jour. Indus, and Eufiin. Chem., 

 5 (1913), No. 6, p. 485).— This method (E. S. R., 24, p. 703) is now recommended 

 for determining ammonia in fertilizers in lieu of the magnesium oxid method, 

 as follows : 



" Two gm. of fertilizer is placed in a 100 cc. graduated flask, about 50 cc. of 

 water added, and then 25 cc. of approximately normal hydrochloric acid. The 

 volume is now made up to 100 cc. with water, the contents of the flask are 

 shaken, and after standing a few minutes are shaken a second time. The flask 

 is now allowed to stand until the heaviest of the undissolved particles have 

 settled. Five cc. of the supernatant liquid is withdrawn by means of a pipette 

 (filtering is not necessary) and transferred to the tube of the Folin apparatus. 

 Two cc. of a saturated solution of potassium oxalate, a few drops of kerosene, 

 and finally 2 cc. of a saturated solution of potassium carbonate are added. 

 The apparatus is immediately closed and air passed through for 10 to 20 

 minutes. The ammonia is collected in a flask or test tube which contains 20 

 cc. of seventieth-normal hydrochloric acid. If the air current is produced by 

 a blast the anunonia is collected in a flask and 25 cc. of water is added to 



