1917] AGBICTJLTURAL CHEMISTRY AGEOTECHNY. 805 



Some laboratory conveniences, A. E. Perkins {Jour. Indus, and Engin. 

 Chem., 9 (1917), No. 1, pp. 57. 58, figs. 4).— The author, at the Ohio Experi- 

 ment Station, describes a special flat-bottomed Kjeldahl flask for use with the 

 extraction apparatus previously described * ; a convenient, satisfactory, and 

 easily assembled burette support ; two convenient pipettes for sampling milk 

 and milk products ; and a novel and convenient drying rack for laboratory 

 glassware. 



Carbon dioxid absorption apparatus, L. G. Wesson (Jour. Indus, and Engin. 

 Cheni., 9 (1917), No. 1, p. 59, fig. 1). — A simple apparatus consisting of a cylin- 

 drical bulb for carbon dioxid absorption with soda lime and a smaller arm 

 attachment to contain the drying agent is described. 



Apparatus for the recovery of bromin, C. H. Collings (Chem. News, IH 

 (1916), No. 2975, pp. 259. 260, fig. i).— An apparatus for the recovery of bromin 

 from laboratory waste liquors and its manipulation are described In detail. 



Note on the recovery of molybdic acid, P. Rudnick and R. D. Cooke (Jour. 

 Indus, and Engin. Chem., 9 (1917), No. 1, pp. 109. 110). — The procedure, which 

 ip similar to that described by Brown', is as follows : 



The phosphomolybdate solutions, after titration, are filtered through glass 

 wool and combined with the filtrates and washings separated from the yellow 

 precipitates. To this, an excess of saturated ammonium phosphate is added 

 and after standing at least over night the supernatant liquid is siphoned off. 

 When a convenient amount of ammonium phosphomolybdate has been collected 

 in this manner it is washed by decantation with hot water and then dried on 

 the steam bath. This material contains approximately 92 per cent of molybdic 

 acid (85 per cent MoOs). Of this dried salt 510 gm. is dissolved in ammonium 

 hydroxid, made by diluting 620 cc. of ammonia (specific gravity 0.9) to 1,000 cc. 

 To this, 85 gm. of magnesium nitrate in 200 cc. of water is added and after 

 settling for two or three hours the filtrate is tested for phosphorus by adding 

 a few cubic centimeters to double the amount of nitric acid (1:2.5). When 

 precipitation is complete the magnesium-ammonium phosphate is filtered off. 

 washed, and the filtrate made up to a volume of 2 liters. The ammonium 

 molybdate solution is then added to the requisite amount of nitric acid and, 

 after standing for some time, filtered. 



Notes in regard to titration of sulphuric acid, C. R. Gyzandeb (Chem.. 

 News. 114 (1916), No. 2975, pp. 260, 26i ) .—Analytical data showing the error 

 that is likely to be introduced when an alkali is standardized with one indicator 

 and then used for acid titrations with a different indicator are submitted and 

 discussed. 



Handling a standard solution of barium hydrate, W. G. Hatnes (Jour. 

 Indus, and Engin. Chem.. 9 (1917). No. 1, pp. 58. 59. fig. 1). — An easily con- 

 structed attachment to the usual siphon arrangement used in filling burettes 

 with standard barium hydroxid solutions and its manipulation are described 

 in detail. 



The use of the Cottrell precipitator in recovering the phosphoric acid 

 evolved in the volatilization method of treating phosphate rock, W. H. Ross, 

 J. N. Cabotheks, and A. R. Meez (Jour. Indus, and Engin. Chem., 9 (1917), No. 

 1, pp. 26-31, fig. 1). — The authors have applied the Cottrell precipitator in re- 

 covering the phosphoric acid evolved in the volatilization method of treating 

 phosphate rock by ignition with coke and silica in an electric furnace The new 

 method is claimed to possess a number of advantages over the scrubbing- tower 

 method now in use. 



1 Jour. Indus, and Engin. Chem., 5 (1913), No. 2, pp. 148, 149. 

 »Jour. Indus, and Engin. Chem., 7 (1915), No. 3, pp. 213, 214. 



