508 EXPEBIMENT STATION BECOBD. 



The method is applicable to the determination of chlorids in blood, serum, 

 ascitic fluid, urine, pleural exudates, gastric juices, etc. 



A rapid method for determining calcium in urine and feces, H. Lyman 

 (Jour. Biol. Chem., 21 (1915), No. 3, pp. 531-556). — A rapid method, consisting 

 of three main steps, (1) isolation of the calcium as calcium oxalate, (2) solu- 

 tion of the calcium oxalate in dilute acid, and (3) precipitation of the calcium 

 as a soap and comparison of the cloud so formed with a standard in a Duboscq 

 colorimeter, is described in detail. 



A simple method for the determination of ammonia in urine, A. A. 

 BoxKEMA (Chem. Ztg., 39 (1915), No. S2-83, p. 519).— The method devised is as 

 follows : 



To 10 cc. of the urine in a 300-cc. Erlenmeyer flask 30 cc. of absolute alcohol 

 is added, together with several small pieces of pumice stone and 0.5 gm. of 

 unslaked lime. The flask is fitted with an adapter to which is attached a con- 

 denser by a piece of rubber tubing. The flask is heated with constant shaking 

 over a free flame and the distillate received in a 50 cc. graduate containing 

 10 cc. of tenth-normal sulphuric acid. When the liquid in the graduate meas- 

 ures 40 cc, the distillation is stopped. The contents of the graduate are trans- 

 ferred to a flask, about 75 cc. of distilled water added, and the excess acid 

 titrated witli tenth-normal alkali, using 1 per cent p-nitrophenol or other 

 indicator suitable for ammonia titrations. Claims made for the method are (1) 

 that ammonia does not exist as ammonium hydroxid in alcoholic solution and 

 hence distills over completely, (2) the distillate always consists of a mixture 

 of water and alcohol, as does the residue in the fla.sk, and (3) urea can not 

 take up water in alcoholic solution and thus form ammonium carbonate. 



The formol titration method of Henriques and Surensen (E. S. R., 23, p. 217) 

 has been slightly modified for the determination of amino acids in urine. 



The gravimetric determination of tannic acid in tanning materials, A. 

 Gawalowski (Ztschr. Analyt. Chem., 5k (1915), No. S, pp. 403-40.5).— In the 

 method described, 50 gm. of bark or 15 gm. of other material, finely ground, 

 is treated in a half-liter flask with 250 cc. alcohol-ether mixture (1 :2). The 

 flask is tightly stoppered and the material allowed to digest at room tempera- 

 ture for at least one day. Ten cc. of the clear extract is evaporated to dryness, 

 taken up with 50 cc. of cold water (whereby the resins are precipitatetl). and 

 25 cc. of the filtrate precipitated with basic copper acetate. The precipitate 

 is filtered on a weighed filter and air dried, later dried to a constant weight in 

 a water bath, and ignited in a stream of air or oxygen until all the copper is 

 changed to copper oxid and then in a stream -of hydrogen to reduce the oxid 

 to metallic copper, and the copper weighed. The difference in the two weights 

 times 100 gives the percentage of tannin present in the material. 



The tannin content of Pacific coast conifers, H. K. Benson and T. G. Thomp- 

 son (Jour. Indus, and Engin. Chem., 7 (1915), No. 11, pp. 915, 916, fig. J).— The 

 experimental data reported show a tannin content of Douglas-fir sawmiill bark 

 of 6.34 per cent, while the cambium layer contained 9.02 per cent. Sawmill 

 bark of Western spruce contained 5.88 per cent of tannin. Fir waste is 

 regarded as a suitable material for use in the tannin-extract industry. 



The application of the Davis spot test in the preliminary examination of 

 creosotes, H. Cioukey (Jour. Indus, and Engin. Chem., 7 (1915), No. 11. pp. 

 923, 92-'t. figs. 2). 



Practical white sugar manufacture, H. C. Prinsen Geeeligs (London: 

 Norman Rodger, 1915, pp. Xn+184, P^s- 5, figs. 28). — This volume gives a com- 

 plete and detailed practical account of the manufacture of white sugar, in- 

 cluding the mechanical details of the process. The subject matter is dividetl 

 into three main parts, (1) clarification of the cane juice, (2) boiling, curing. 



