AGEICULTXJEAL CHEMISTEY AGROTECHNY. 203 



strat between 0.4 and 2 per cent. There is no relation between the degree of 

 dissociation and the rate with which basic caseinates are hydrolyzed by 

 trypsin, as in the solikions employed the caseinates of the alkalis are almost 

 completely dissociated, while the caseinates of the alkaline earths are only 

 about 50 per cent dissociated, yet both series of ' salts ' are hydrolyzed by trypsin 

 at approximately the same velocity. There is evidence of rapid autohydrolysis 

 in solutions of neutral and basic caseinates of the alkalis and alkaline earths." 

 Method for obtaining natural soil solutions, F. H. H. Van Suchtelen 

 (Jour. Landw., 60 {1912), No. 4, PP- 369, 370).— For preparing a soil solution 

 for bacteriological purposes which will represent natural conditions, the follow- 

 ing procedure is recommended : 



A stratum of fairly moist soil having a known moisture content is spread over 

 a nonhygroscopic asbe.stos layer previously washed vrith ether and dried, con- 

 tained in a large Buchner filter. The soil is pressed down slightly with a 

 rubber stopper, cooled paraffin oil is then poured over it until it is entirely 

 covered, and a suction pump connected to produce a gentle suction. The fluid 

 obtained m the flask of the suction pump is heated to 40° C. to reduce the 

 viscosity and enhance the separation of the fluids, transferred to a pointed 

 glass, and centrifuged. The watery solution is then drawn ofE and used for 

 the purpose intended. The paraffin oil, free from bubbles, can be used again. 



The soil water displaced by the oil, according to the author's experiments, 

 constitutes about 50 per cent of the total water capacity of the soil. 



This work will be reported on more fully in a later publication. 



Efflorescence on lava bricks, W. McGeorge { Hawaii Sta. Bpt. 1912, p. 59). — 

 An efflorescence was noted on bricks made from ground lava rock, which in 

 some cases made the brick walls appear as though they had been in the path of 

 a snowstorm. The efliorescence was found to be composed of the carbonates or 

 bicarbonates of sodium and iwtassium. 



" The brick are made by pressing the ground rock after a slight addition of 

 lime and dampening of the mixture. They are then dried under steam pressure. 

 The conclusion reached was that the lime and the subsequent di-ying tempera- 

 ture cause the trouble. Sodium and potassium carbonates are not normal 

 products of lava disintegration, although some of the vesicles in lava rock con- 

 tain a coating of carbonate. Potassium and sodium occur in basaltic lava in the 

 form of complex silicates. The lime at the temperature of the drying kiln 

 probably replaces the sodium and potassium m these silicates and forms caustic 

 soda and potash, which in turn are converted on contact with the air into 

 carbonates and bicarbonates." 



New reduction methods in volumetric analysis, E. Knecht and Eva Hib- 

 BEBT {London, New York, and BomMy, 1910, pp. X+iOS, figs. 3).— This contains 

 a series of analytical methods, almost all of which have been published in other 

 journals. 



The methods for organic substances are for nitro compounds, azo compounds, 

 rtyestuffs which yield colorless leuco compounds, sugars, coloring matters in 

 dyed cotton fabrics, etc. Methods are also included for inorganic substances 

 such as hydrogen peroxid and certain per-acids, chlorates, perchlorates, nitrates, 

 hydroxylamin, oxygen in water, and hydrosulphites.' 



Methods for the preparation of neutral solutions of ammonium citrate, 

 J. M. Bell and C. F. Cowell {Jour. Amer. Chem. Soc, 35 {191S), No. 1, pp. 

 49-54, figs. 2). — After pointing out the advantages to be derived by using the 

 conductivity method (E. S. R., 26, p. 709; 27, p. 110), 2 further methods are 

 presented for determining the neutral point of ammonium citrate solution, 

 neither of which requires careful regulation of the temperature. 



