312 EXPERIMENT STATION EECOED. [Vol. 41 



An instrument for the determination of small quantities of carbon monoxid 

 in hydrogen, E. K. Rideal and H. S. Taylor {Analyst, ^^ (1919), No. 516, pp. 

 89-94, flO'^- 2). — An instrument is described and illustrated which has been 

 adapted for the continuous analysis of hydrogen supplies and for automatic 

 registration of the carbon monoxid content. The principle employed is that 

 of preferential catalytic combustion of tlie carbon monoxid with a small amount 

 of added oxygen, the carbon dioxid formed being suitably absorbed and esti- 

 mated. The preferential combustion of the carbon monoxid was found to 

 occur in tlie presence of metallic oxids and to be increased by using a mixture 

 of several oxids. A mixture of iron and chromium oxids with small quantities 

 of cerium and thorium oxids proved very satisfactory. 



By means of this instrument it has been found possible to determine and 

 record very quickly minute traces of cai'bon monoxid in liydrogen and also 

 to differentiate rapidly between varioiis catalytic agents. 



Analytical method for determining' eflB.ciency of ammonia oxidation, I>. P. 

 Gaillakd (Jour. Indus, and Enyin. Chcin., 11 (1919), No. 8, pp. 745-7^7, fin. 1). — 

 The efficiency of ammonia oxidation is determined by a comparison of the 

 percentages by weight of combined nitrogen in the entrance and exit gasea 

 of the converter. In the " bulb " method of analysis here described a sample 

 of the gases to be analyzed is drawn into a previously weighed evacuated 

 bulb, and a second weighing is made to obtain the weight of the sample. 

 In the case of the entrance gases, the combined nitrogen in the form ot 

 ammonia is determined by absorption in water and subsequent titration 

 with N/10 sulphuric acid. In the case of the exit sample, after the intro- 

 duction of water, oxygen is drawn in and the bulb shaken for several minutes, 

 after which the liquid and washings are transferred to a beaker and titrated 

 with N/10 sodium hydroxid. 



The detailed procedure is described in full and suggestions are given for 

 variations in procedure. The average precision of a single efficiency determi- 

 nation in duplicate is thought to be within ± 0.75 per cent. The chief merit 

 of the method is its simplicity, both in the analytical work and in the 

 calculations. 



Adaptation of the Mohr volumetric method to general determinations of 

 chlorin, L. Yoder (Jour. Indus, and Enyin. Chem., 11 (1919), No. 8, p. 755). — The 

 author at the Iowa Experiment Station has developed a modification of the 

 Mohr method of determining chlorids which has proved applicable to rapid 

 determinations of chlorin in various materials, particularly in organic products 

 containing small amounts of the element. The procedure adopted is as follows: 



" To the sample is added 5 cc. of a 30 per cent solution of calcium acetate 

 with sufficient distilled water to thoroughly saturate the material. The mix- 

 ture is evaporated to dryness at 120° C. and ignited at a temperature not 

 over 450°. The cooled residue is thoroughly moistened with a few cubic centi- 

 meters of a 10 per cent solution of ferric acetate, and again evaporated 

 to dryness and ignited below 450°. The residue is triturated with hot water, 

 filtered, and washed until free from chlorids. The filtrate is evaporated to 

 dryness or nearly to dryness and taken up with .lust sufficient hot water 

 to insure complete solution of the chlorids when cooled. After the addition 

 of 2 or 3 drops of potassium chroinate, the solution is titrated with 0.05 N 

 silver nitrate." 



Tables are given of the results obtained in the determination of chlorin by 

 this method and by the gravimetric method in different samples of cow feces, 

 mixed grains, and alfalfa hay. The results were in all cases well within 

 the limits of experimental error. 



