SUBjl'XT IJST OF ABSTRACTS. 



CHEMISTEY. 



The determination of citric-acid soluble phosphoric acid in Thomas slag, 



O. PxiriviiKK (/ '/((';/(. '/t(j., 37 {J903) , Xu. 100, p. 1J25). — A method of tes^tino; the citric 

 acid extrat-t of Thomas slag for sihcic acid is descril^ed as follows: To 100 cc. of the 

 extract in a 200 cc. flask add 75 cc. of ammoniacal citrate solution, boil over the direct 

 flame, and allow to stand for 5 to 10 minutes. If no precipitate soluble in hydrochloric 

 acid separates out, silicic acid is not present in sufficient amount to interfere with the 

 accuracy of the determination, and phosphoric acid may be determined directly in 50 

 cc. of the extract. If a flocculent precipitate of silicic acid is formed the solution is 

 acidified with dilute hydrochloric acid, cooled, and filtered. To 100 cc. of the filtrate 

 20 cc. of magnesia mixture is added, the mixture shaken one-half hour, and the 

 operation continued in the usual way. 



The inapplicability of the so-called Maercker-Buhring solution to the 

 determination of total phosphoric acid in Thomas slag, 1 1. Svoboda {Chrrn. 

 Ztg., 27 {1903), No. 98, pp. 1203-1205). — Comparative tests of the Maercker-Bii bring 

 solution (1,500 gm. of citric acid and 5 liters of ammonia of 0.91 sp. gr. made to a 

 volume of 15 liters) with the old method of separate addition of citric acid and 

 ammonia are reported. The results by the new method were as a rule higher than 

 those l)y the old. This is attributed to the presence in the precipitate of silicic acid 

 dissolved from the glass vessels in which the solution was kejit. 



A table for the calculation of phosphoric acid from magnesium pyro- 

 phosphate, T. Kampfer [Ztsrlir. Analyt. Chcm., 43 {1904), No. 1, App.,pp. 25). 



The organic matter in soils and subsoils, F. K. Cameron and J. F. Breazeale 

 {Jour. Amer. Chem. Soc, 26 {1904), No 1, j)p. 29-45). — Of the 3 methods in com- 

 mon use for the determination of organic matter in soils, those based on loss on 

 ignition and humus content are condemned as unsatisfactory, and the third or com- 

 bustion method, which consists in burning the organic matter either in a tube in a 

 furnace or by powerful oxidizing agents, such as chromic acid or potassium perman- 

 ganate, and collecting and determining the carbon dioxid liberated, is considered 

 most accurate and reliable. 



In the method recommended "a sample of the soil, usually about 10 gm., is care- 

 fully weighed and brought into the combustion flask. If the sample be rich in 

 organic matter, it has been found advisable to introduce also some sand, previously 

 ignited before the blast, and in an amount dependent roughly upon the apparent 

 quantity of organic matter in the soil. From 5 to 10 gm. of pulverized potassium 

 bicromate are then added, and the whole mixed thoroughly by shaking, care being 

 taken to prevent any of the mixture adhering to the sides of the flask above the 

 level of the mixture. The flask is closed securely by the stopper, and a gentle stream 

 of air drawn through the whole apparatus by means of the aspirator. 



"When this stream of air has been passing for about 10 minutes, concentrated sul- 

 phuric acid (sp. gr. about 1.83) is slowly and cautiously run in by means of the 

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