610 EXPERIMENT STATION RECORD. 



A method of estimating calcium, carbonate in soils, H. S. Shrewsbuby 

 iPharm. Jour. [London], 4. ser., 34 (1912), No. 2527, p. 394).— The method is as 

 follows : • 



" Ten gm. of finely divided air-dried soil is treated with 100 cc. of roughly 

 quarter-normal acetic acid, rotating the flask every time most of the soil 

 settles, during 10 minutes. The same weight of soil is treated in the same 

 manner with 100 cc. of distilled water. Twenty-five cc. of the filtrate from each 

 extraction is evaporated in a platinum dish, ignited at a bright red heat for 30 

 minutes, and the residues of (principally) lime dissolved in 10 cc. or more if 

 necessary of decinormal acetic acid. Titrating back with decinormal soda or 

 potash and phenolphthalein gives the cubic centimeters equivalent to the lime 

 in the residues. Subtracting the volume obtained from the control (which 

 will not exceed 0.1 cc. in most soils), the remainder multiplied by 0.2 gives 

 the percentage of calcium carbonate in the soil. The control experiment 

 eliminates such bodies as the carbonates or organic salts of the alkalis, soluble 

 organic calcium salts, calcium nitrate, etc. Acetic acid is chosen for the 

 titration as it does not dissolve ignited iron oxid." 



The results of tests with 4 soils are also included. 



The estimation of ammonia in carbonated waters, G. D. Elsdon and 

 K EvERS {Pharm. Jour. [London], .}. sen, 34 {1912), No. 2527, pp. 394, 395).— 

 The presence of carbon dioxid in water seriously interferes with the determina- 

 tion of ammonia in such wtiters by the Nessler method. The following method 

 will overcome much of the difficult}' : 



After shaking the flask containing the water by the usual method, 500 cc. 

 is transferred to a distilling flask and 5 cc. or more of normal sulphuric acid, 

 according to the alkalinity of the water, is added. An equivalent amount of 

 normal sodium hydrate and a sufficient amount of sodium carbonate are then 

 added and the usual procedure for determining free and albuminoid iimmonia 

 followed. 



Nitric nitrogen in mixed fertilizers, S. S. Peck {Jour. Indus, and Engin. 

 Cheni., 3 {1911). No. 11, pp. 817, 8/8).— The reliability of the modified Gun- 

 ning and Kjeldahl methods for determining total nitrogen in a mixture con- 

 taining an addition of nitrate of soda was studied. 



The author believes on the basis of his findings with a new procedure, 

 which is given below, that good results can be obtained with the Gunning 

 method providing the moisture content of the sample is not too high. There 

 was no loss of nitrogen noted in a mixed fertilizer containing sodium nitrate 

 and sodium phosphate, which was kept for a period of 4 months. The method 

 used is as follows : 



Ten gm. of the fertilizer w.ns transferred to a beaker and stirred with some 

 water for about 1 hour. The mixture was then filtered, and the residue 

 washed until a total bulk of 500 cc. of filtrate was obtained. Twenty-five cc. 

 of the filtrate was then distilled with sodium hydrate for ammonia nitrogen, 

 25 cc. more reduced with iron and sulphuric acid for determining the nitric 

 nitrogen, and a further 25 cc. used for determining the total nitrogen by the 

 Kjeldahl method (using a 500 cc. flask with mercury, sulphuric acid, and 

 potassium sulphate). 



The nitrogen in the residue which remained on the filter paper was also 

 determined but it was necessary first to render it air dry. 



Report of the committee on phosphate rock, W. D. Richardson et al. {Jour. 

 Indus, and Engin. Chem., 3 {1911), No. 10, pp. 783-787). — This is a report of 

 the committee appointed by the division of fertilizer chemistry of the American 

 Chemical Society on the analysis of phosphate rock. It includes the reports 



