412 EXPERIMENT STATION RECORD. [Vol.38 



glycerol and two volumes of water. They are then removed, dried, and used in 

 a Soxhlet apparatus for an hour. Thus treated they may be used to advantage 

 with any solvent in the vapor of which water and glycerol are not readily 

 soluble. They should be stored at ordinary temperature, as a warm dry atmos- 

 phere causes them to shrink and harden. 



The preparation of 1/100-normal permanganate solutions, J. O. Halveeson 

 and O. Beegeim {Jour, hidus. and Engin. Chem., 10 (1918), No. 2, pp. 119, 

 120). — New technique for the preparation of Tw-Jiormal solutions of potassium 

 permanganate is described and a table given of the keeping qualities of dilute 

 permanganates and of oxalic acid solutions used as standards. 



A proximate quantitative method for the determination of rubidium and 

 caesium in plant ash, W. O. Robinson (Jour. Indus, and Engin. Chem., 10 

 {1918), No. 1, pp. 50, 51). — This method is based on the removal of a large part 

 of the potassium chlorid by fractional precipitation with platinic chlorid and, 

 further, by strong hydrochloric acid. The resulting solution is compared spec- 

 troscopically with a standard solution. 



The method is as follows: Twenty or more gm. of the dry plant are ashed 

 in a muffle below 525° C. The ash is dissolved in hydrochloric acid, the excess 

 evaporated, freshly slaked lime added, and the mixture boiled and filtered. 

 The calcium is precipitated with ammonia and ammonium carbonate, the com- 

 bined filtrates evaporated to dryness, and ammonium salts expelled. The 

 alkali chlorids are filtered off with hot water, a few drops of hydrochloric acid 

 added, and then about 0.05 gm. of platinic chlorid. The solution is evaporated 

 to pastiness, a small amount of hot water added to dissolve the \inchanged 

 chlorids of potassium and sodium, and the chlorplatinates of the rare metals 

 are washed on to the asbestos pad in a small carbon filter with 80 per cent 

 alcohol. The filter is then connected to a hydrogen generator and the platinic 

 chlorids reduced by heating with a Bunsen burner. The chlorids are washed 

 through the filter with hot water, the filtrate evaporated to pastiness, and the 

 mass taken up by a few drops of hydrochloric acid, flltei'ed into tiny vials, and 

 made up to volume. Standards are made with known amounts of caesium and 

 rubidium chlorids and an -excess of potassium chlorid. The comparison is 

 made by introducing a coil of platinum wire of sufficient size to withdraw a 

 large drop. The coil is carefully dried and the unknown solution matched with 

 a standard by means of the brilliancy of the hue. 



Method for the determination of the amount of sug'ar in baked articles 

 {Analyst, 42 {1917), No. ^98, pp. 294, 295).— This is the official method proposed 

 by the Government Laboratory (England) for the determination of the amount 

 of sugar present in baked articles examined under the Cake and Pastry Order. 

 The preparation of samples and the methods of analysis are given in detail. If 

 necessary to use a clearing agent, basic lead acetate followed by sodium sul- 

 phate, or alumina cream, or copper sulphate solution may be employed. The 

 sugar is inverted with hydrochloric acid and the reducing sugar determined 

 either by gravimetric or volumetric process and calculated as cane sugar. If 

 the article contains fruit, the fruit is removed and analyzed separately for its 

 sugar content. 



A deduction of 3 per cent is made for sugars naturally present in flour or de- 

 rived from flour in the course of baking, and an allowance of 2 per cent is 

 made to provide for variations in sampling, in methods of analysis, and in the 

 amount of sugar in the different materials employed. 



Detection of alum in flour, L. Medri {Staz. Sper. Agr. ItaL, 49 {1916), No. 

 11, pp. 597-601). — A delicate method for detecting alum in flour is described. 

 The principle involved is the formation of an insoluble color lake with cochineal 



