712 EXPERIMENT STATION RECORD. [Vol. 37 



lation are described. The flask is pear-shaped, with a wide-mouthed stopcock 

 at the bottom and a heavj- glass tubing leading oft" to the suction pump from 

 near the flask mouth, which is of a size suitable to take the filtering funnel. 



Advantages claimed for the flask are better air seals than those obtained 

 with the bell-jar type of filter, and easy removal of the filtrate and washing of 

 the flask, thus practically eliminating the danger of contamination. 



A simple improvised apparatus for hydrogen sulphid precipitation under 

 pressure, A. V. Fuller (Jour. Indus, and Engin. Chem., 9 {1911), No. 8, pp. 792. 

 793, fig. 1). — The apparatus described consists of an ordinary 500-cc. Kipp 

 generator provided with a two-holed rubber stopper which carries a one-way 

 stopcock and a small-bore glass tube about 3 ft. long which terminates at its 

 upper end in a reservoir bulb of about 100 cc. capacity. The lower end of this 

 tube extends several inches below the acid level. The gas outlet is fittetl with a 

 rubber stopper carrying a two-way stopcock. The manipulation of the apparatus 

 is described. 



It is noted that the precipitates obtained appear very granular and settle 

 readily. The point of saturation is easily determined by rotating the flask 

 and noting the absence of gas bubbles. 



A method of ashing organic materials for the determination of potassium. 

 P. L. Blumenth.xl. a. M. I'ETEB, D. J. Uealy, and E. J. Gott (Jour. Indus, and 

 Engin. Chem., 9 (1917), No. 8, pp. 753-756). — To reduce materially losses by 

 spattering and volatilization in ashing organic material, the authors, at the Ken- 

 tucky Experiment Station, have found that direct evaporation of the sample 

 with nitric and sulphuric acids preliminary to burning off organic matter ha.s 

 l.mved the best n)ethod for securing uniform results. Simple moistening of the 

 sample witli sulphuric acid was found not to be suflicient, and enough acid must 

 be added to oxidize the carbon and to convert all inorganic elements present to 

 sulphates. This conversion of the pota.ssium .salt pre.sent in the material to 

 the sulphate reduces the volatilization losses to a minimum. 



Burning off the carbon in a muffle furnace yielded more uniform results than 

 direct heating over a free flame. 



The data are submitted in tabular form and discussed. 



A practical revision of the cobalti-nitrite method for the determination 

 of potash, 11. C. U.wv and E. H. Schwartz (Jour. Indus, and Engin. Cluni., 9 

 (1917), No. 8, pp. 785, 786). — The following revision of the proceilure previously 

 described by Bowser (E. S. R., 22, p. 510) i.s submitted: 



To a 2-gm. sample of raw material 0.5 gm. of ammonium chlorid is added and 

 thoroughly mixed in a mortar. Four gm. calcium carbonate is then adiled and 

 the contents of the mortar further mixed and gi'ound. The mixture is trans- 

 ferred to a 20-cc. platinum crucible, the bottom of which has been covered with 

 a generous layer of calcium carbonate, usually about 2 gm., the contents of the 

 crucible are covered with about 2 gm. of calcium carbonate, and the heating 

 and sintering carried out as in the .7. Lawrence Smith method. After the mass 

 has been slakeil in a small ca.sserole it is placed on a hot-water plale and 

 heated to boiling, filtered into a flat-bottomed porcelain dish, and the precipitate 

 washed three or four times with very hot water. An excess of acetic acid (5 

 to 10 cc.) is added to the filtrate and the solution then evaporated ou a steam 

 bath until no odor of acetic acid remains. 



The residue is taken up with a little hot water and the sides of the dish 

 tlioroughly washed. From 10 to 15 cc. of the cobalt reagent is added and the 

 liquid evaporated on a steam bath to a pasty consistency. It is removed from 

 the bath, cooled, and about 30 cc. of cold water added, breaking up the precipi- 

 tate thoroughly. The precipitate is then filtered through an asbestos paddeil 

 Glooch crucible, washed once with cold water, the contents of the crucible trans- 



