608 EXPERIMENT STATION EECOED. 



The method of analysis of solutions obtained by means of strong acids is 

 severely criticised, the following method being used in the author's investiga- 

 tions here reported : At least 1 kg. of the soil in its natural condition, calcu- 

 lated on a water-free basis, is shaken for an hour with 2 liters of a 2 per cent 

 hydrochloric-acid solution in a rotary apparatus of similar construction as, but 

 of larger dimensions than, the Wagner apparatus for determination of citrate- 

 soluble phosphoric acid in Thomas phosphate, and 1 liter Altered off. This 

 amount is then evaporated to dryness to separate out silica and the ordinary 

 course of analysis followed for the determination of the other constituents. 

 Nitric acid is determined in a separate sample which is digested with water and 

 the filtrate examined by the Ulsch method. Ammonia is determined in a sample 

 digested with water acidulated with sulphuric acid. Organic nitrogen is deter- 

 juined according to the Kjeldahl method. 



It was found that soils treated with a 4 per cent, and even a 2 per cent, 

 hydrochloric-acid solution become sterile for the time being for all crops 

 experimented with except potatoes, which can make a sickly growth therein. 

 The reason why barley, at least, does not find sufficient food in the soil extracted 

 in this manner is that soil so treated contains too little lime. During the 

 second to fourth year after extraction, potatoes, oats, and barley develop nnich 

 3uore luxuriantly in extracted soil than in a good arable soil, the explanation 

 given being that the available plant food the first year is removed by the acid 

 digestion and subsequent washing with water, whereas new plant food is formed 

 later on from the organic raw material which remained in the soil. The nitric 

 and sulphuric acids in the soil, in the author's opinion, are obtained from 

 organic material, and phosphoric acid from phosphorus in humus substances. — 

 y. w. woLi,. 



Quantitative determination of potassium, It. 1'ajetta (G«c. Chhii. ItuL. 

 36 (1006), II, pp. 150-156; ahs. in Jour. 8oc. Chriii. Indus., 25 {1906), No. 21, 

 p. 1068). — The author finds that Tarugi's persulphate method of determining 

 potash is inaccurate on account of the solubility of the potassium persulphate 

 in solutions of sodium sulphate. 



The solubility of gypsum in phosphoric acid solutions, W. C. Taber 

 {Jour. Phys. Chem., 10 {1906), p. 593; ahs. in Chcni. Ahs., 1 {1901), No. 1, 

 p. 21). — It was found that at a temperature of 25° the solubility of gypsum 

 increased with the concentration of the phosphoric-acid solution until a maxi- 

 mum was reached at about 230 gm. of phosphorus pentoxid per liter, when the 

 solul)ility was about four times that in pure water. Beyond this point the 

 solubility regularly decreased with the increase of the acid content. 



The detection of nitric and nitrous acids, II. AY. Wagner {Pliarm. Cciitral- 

 hallc, JfS {1907), No. 1, pp. 5-7). — The thymol, resorcin, and especially the 

 l>henol reactions for these acids are described. 



Nitron: A new reagent for nitric acid {Merck's Ann. Rpts., 19 {1905), 

 pp. 151, 152; (lbs. in Chem. Neics, 94 {1906), No. 2'i5Jf, p. 271). — A description is 

 given of the composition, properties, and method of use of this reagent. (See 

 also E. S. R., 16, p. 9ir>.) 



Determination of nitrates, F. S. Sinnatt {I'roc. Chem. Soc. London, 22 

 {1906). p. 255; ahs. in Analysi, 31 {1906), No. 369, p. US; Jour. Soc. Chenu 

 Indus., 25 {1906), No. 2-',, p. 1227; Chem. Ahs., 1 {1907), No. 2, p. I'i9).— 

 Knecht and Ilibbert's method for picric acid was applied to the determination 

 of potassium nitrate with a fair degree of accuracy. The method depends on 

 the conversion of the nitrates into picric acid by means of phenolsulphonic 

 acid, the picric acid being determined by titanium trichlorid. 



On the distillation of ammonia with and without condensing in the 

 Kjeldahl method of determining nitrogen, E. Pescheck {Jour, Landw., 54 



