RECENT WORK IN AGRICULTURAL SCIENCE. 



AGEICULTTJRAL CHEMISTRY— AGEOTECHNY. 



Chemical-technical analysis, G. Lunge, E. Berl et al. {CJiemisch-technische 

 Untersnchungsmethoden. Berlin, 1910, vol. 2, 6. ed., rev. and enl., pp. ZF/+ 

 869, figs. 138; Sup. pp. 8). — This is the second volume of the work previously 

 noted (E. S. R., 22, p. 508), and deals with physical, mechanical, and chemical 

 methods for the analysis of cyanogen compounds, clays, glass, cement, water, 

 sewage, soils, air, iron and other metals, calcium carbid, and acetylene. 



Method for estimating' nitric acid, O. Angelucci {Ahs. in Chem. Ztg., 3^ 

 (1910), No. 112, p. 9,9/,).— In this method from 0.2 to 0.5 gm. of the substance 

 is mixed with 3 gm. of fused and powdered lead chromate. The mixture is 

 then put in a porcelain boat and inserted in a combustion tube which is open 

 at both ends. On one side of the tube are placed successively a 30 cm. layer 

 of metallic copper, copper oxid (15 to 20 cm.), and a copper netting (5 to 6 

 cm.), and it is then connected with an azotometer (nitrometer). Carbon 

 dioxid is passed through the apparatus with a capillary tube, and when the 

 air has been displaced the combustion tube is heated to from 400 to 500° C. 

 The nitrogen oxid vapors formed are reduced by the metallic copper, and the 

 pure nitrogen is collected and measured in the azotometer. 



A simple method for the estimiation of potassium, A. Grete {Mitt. Lcbensm. 

 TJritersuch. u. Uyg., Sehtvciz. Gsndlitmmt., 1 {1910), No. 5, pp. 295-297; abs. in 

 Chem. Ztg., 34 {1910), No. 117, p. WJiO).—This is a simplification of the Finke- 

 ner-Neubauer method (E. S. R., 12, p. 714), and consists of boiling 20 gm. of 

 the air-dry substance in a liter bottle until solution has taken place. Sodium 

 hydroxid and ammonia are then added until all the precipitable substances 

 are thrown down and the reaction is slightly alkaline toward pbenolphthalein. 

 The mixture is cooled and filled up to the mark with water, and the precipitate 

 allowed to settle. 



A measured quantity of the clear fluid is evaporated to dryness in a beaker 

 (resistant glass), and if necessary with the addition of a little sodium hydrate 

 to remove the remaining ammonia. If amids are present these are broken 

 down with a little sodium hypochlorite or chlorin water, and where much 

 organic matter is in the mixture this is oxidized in a platinum dish with a little 

 sulphuric acid. The residue is acidified with hydrochloric acid, treated with 

 an excess of platinic chlorid, and evaporated to a small bulk. In order to 

 wash the potassivim platinic chlorid thoroughly and remove the sulphates and 

 chlorids which may be present, the residue is taken up with a little water, 

 100 cc. of 96 per cent alcohol added, and shaken. The precipitate formed is 

 collected in a Gooch crucible by the aid of suction, washed several times, dis- 

 solved in water, and magnesium chips and sulphuric acid added to reduce the 

 platinum. The mixture is then filtered through a Neubauer-Gooch crucible 

 106 



