204 EXPERIMENT STATION KECORD. 



A new method for detecting the reducing and oxidizing properties of bac- 

 teria, W. H. ScHULTZE {Centbl. Bakt. [etc.], 1. Abt., Grig., 56 (WIO), No. 5-6, 

 pp. o'i.'i-551; abs. in Jour. Chem. 8oc. [Londoni, 100 (1911), No. 579, II, p. 61). — 

 For detecting reductases an agar medium is prepared as follows: "Concen- 

 trated aqueous sodium hydroxid is added drop by drop to 100 cc. of boiling 

 water containing 1 gm. of a-naphthol until the latter is dissolved. On cooling, 

 more sodium hydroxid is added until the solution again becomes clear and 

 light brown in color. The solution is then mixed with a 1 per cent solution 

 of p-nitrosodimethylanilin (equal volumes), filtered, and mixed with about two- 

 thirds the volume of ordinary nutritive agar (liquid) and poured into Petri 

 dishes." 



For preparing the oxidase-detecting medium a well-filtered mixture of equal 

 volumes of a 1 per cent solution of a-naphthol prepared in the manner described 

 fibove and a 1 per cent solution of paraphenylendimethyldiamin hydrochlorid is 

 added to about 3 parts of liquefied nutritive agar. As this preparation becomes 

 blue in a few hours it is necessary to prepare it each time when required. 



A contribution to catalase estimation, O. Laxa (Ztschr. Vntersuch. Nalir. u. 

 Genussmtl., 21 (1911), No. 7, pp. 417--'i20, fig. 1; abs. in Chan. ZentbL, 1911, 

 I, No. 22, pp. 1611, 1612). — ^This is a description of an apparatus which consists 

 of a graduated tube of 20 cc. capacity. At its lower end it tapers into an open 

 point and to its upper end is affixed a simple stopcock. When conducting the 

 test the author mixes 15 cc. of milk with 5 cc. of a 1 per cent solution of hydro- 

 gen peroxid and draws the mixture up into the tube until the milk is a little 

 above the cock, then closes the cock and holds the apparatus sideways. As 

 the oxygen begins to accumulate the milk mixture drops from the apparatus. 



For comparison Ivoniug's apparatus and Burri and Staub's apparatus (E. g. 

 R., 21. p. 212) were used. The method agreed M^ell with the former, but with 

 the latter a variation corresponding to 2.2 cc. was found. 



Estimation of nitrates by the phenol-sulphonic acid method, H. Cakon and 

 D. Raquet (Bui. Soc. Cltim. France, i. ser., 7 (1910), pp. 1021-1025; abs. in 

 Analyst, 36 (1911), No. 419, pp. 84, 85). — ^A simple way of overcoming the effects 

 of chlorids in this test (E. S. R., 21, p. 8) has been found to be by the use of a 

 freshly prepared solution, and conducting the test as follows : " To 1 cc. of 90 per 

 cent phenol, 10 cc. of sulphuric acid is added, and 1 cc. of this mixture is used 

 for the test. Chlorin up to 10 parts per 100,000 is then without effect. It is 

 important that the residue from the water and that from the standard solution 

 be treated alike. If the former be cooled in a desiccator, and the latter on the 

 bench, nitric-anhydrid will be overestimated ; and if the procedure be reversed, 

 it may be underestimated by more than 50 per cent." 



Quantitative separation of barium, strontium, and calcium, J. L, M. Van 

 DEK Horn Van den Bos (Chem. Weelcbl., 8 (1191), No. 1, pp. 5-10; Chem. 

 ZentbL, 1911, I, No. 18, pp. 1379, 1380; abs. in Analyst, 36 (1911), No. 424, p. 

 364)- — The diluted solution containing the 3 elements is acidified with acetic 

 acid. The barium is precipitated as a chromate with ammonium chi-omate, and 

 after evaporating the filtrate almost to dryness, and dissolving out the calcium 

 present with .50 per cent alcohol, the strontium is determined as chromate. 

 The calcium is determined in the alcoholic filtrate. 



An optional volumetric method is also given. 



The separation and estimation of barium associated with calcium and mag- 

 nesium, by the action of acetyl chlorid in acetone upon the mixed chlorids, 

 F. A. GoocH and C. N. Boynton (Amer. Jour. Sci., 4- ser., 31 (1911), No. 183, 

 pp. 212-218). — From this work "it appears that this method, which rests upon 

 the action of a 4 : 1 mixture of acetone and acetyl chlorid upon the concentrated 



