AGRICULTURAL CHEMISTRY. 109 



Z.tg., 30 (1906), No. 55, pp. (SSJf, GS5 ; abs. in Chcni. ('mm., 1006, II, No. 0, p. 

 558; Aintlijt<t, SI {1906), No. 366, p. 813). — The iiutliDr employs a modification 

 of Fi't'st'iiius's so-called shurt motbod, in which the potassium platinum clilorid 

 is reduiocl by means of nascent hydrogen and the separated platinum is weighed. 



In the luetbod proposed the solution of the potash salt is evaporated directly 

 with pi; ti'.iuni chlorid without previous precipitation with barium chlorid. The 

 potassium platinum chlorid obtained is treated as directed by Fresenius, being 

 washed fri^m the filter into a small beaker and the particles remaining on the 

 filter dissolved in hot water. An excess of magnesium powder is added and the 

 solution gently heated. The precipitate of platinum is collected on a filter and 

 any excess of magnesium is removed by washing with dilute hydrochloric acid. 

 The jjlatinum is then dried, ignited, and weiglied. 



If nuignesium and calcium sulphate are present these are removed by washing 

 with 5 per cent nitric acid. It is stated that in a series of tests of the method 

 lesults were obtained which agreed well with those .vielded by the Fresenius 

 and Finliener-Xeubauer methods. 



A few observations on elementary analytical determination of ash, F. von 

 Ko.xKK {('hviii. Ztfi., 30 {1906), No. J,6, pp. 567, 568; abs. in Chem. Centbl., 1906, 

 II, No. 7, ;>. 631). — By combining ash determination and analytical combustion 

 in one operation the ash content is always higher than by ordinary incinera- 

 tion. By heating the ash obtained in the combustion in the air the weight is 

 reduced to that obtained in ordinary determinations. The difference is said 

 to be due to incomplete dissociation of carbonates of alkalis and alkaline earths, 

 to the variation in volatility of the alkaline salts, and to various minor causes 

 which are enumerated. 



Estimation of carbon in soils and kindred substances, A. D. Hall, N. H. J. 

 MiLLKR, and N. M.\rmu {.Jour. Chem. Soc. [London], 89 {1906), No. 522, pp. 

 595-')91, fig. 1). — The authors tested Wolff's method of determining organic 

 carbon by oxidizing with a mixture of chromic and sulphuric acids, and found 

 Ihat while this method in its original form gave results which were much too 

 low, by the addition of a short tube containing red-hot copper oxid to complete 

 the combustion the whole of the carbon in the soil could be obtained as carbon 

 dioxid. The carbon dioxid evolved is absorbed in dilute caustic alkali in a 

 lieiset tower and determined by double titration with phenolphthalein and 

 methyl orange, as suggested by Hart. 



A method of determining hydrogen peroxid and ferrous salts and other 

 reducing agents, W. E. Mathewso.n and J. W. Calvin {Anicr. Chem. Jour., 36 

 {1906), No. 2, pp. 113-111). — The yellow compound formed by the action of 

 hydrogen peroxid upon soluble titanium compounds is instantly decomposed by 

 reducing agents. The authors have utilized this fact in devising a method for 

 detennining reducing agents by titrating against a standard solution of hy- 

 drogen peroxid and vice A-ersa, a titanium salt being used as an indicator. The 

 results rei)orted in this paper were obtained with ferrous ammonium sulphate 

 and sodium nitrite. 



On the Polenske method for the detection of cocoanut oil in butter, 

 S. KiDEAL and II. (J. IIarkison {Analyst, 31 {1906), No. 365. pp. 25Jf-260, fig. 1). — 

 This method (E. S. K.. 15. p. 850) depends upon the relation of the insoluble to 

 the soluble volatile fatty acids, which the authors do not find to be as constant 

 in pure English butters as was found by Polenske. 



For pure butter obtained from different localities in England during .Tune and 

 July the Polenske numbers varied from 1.6 to 2.15. Samples taken fortnightly 

 from the same dairy for nearly a year showed variations from 1.2 to 2.75. The 

 average Reichert-Meissl and Polenske numbers for the pure English butters 

 3— No. 2—06 2 



