SOMETHING NEW in GENERATING HYDROGEN SULFIDE A. H. PREZIOSO Youngstown College, Youngstown, Ohio
A
COMMON problem confronting the heads of chemistry departments in many schools is the installation of an inexpensive hydrogen sulfide generator, which produces a sufficient supply of gas under constant pressure to meet the demands of thirty or forty students in qualitative analysis. The generator described is similar to other generators, with a few modifications which have been worked out by Dr. E. D. Sadder, head of the chemistry department a t Youngstown College. The apparatus, in
into bottles D. The length of the manometer tube and the lengths of the tubes leading from bottles C to D are such that wben any amount of gas is generated, the pressure in the manometer tube and in the delivery tubes is quickly equalized. As the students use the gas by means of outlets E, the pressure will obviously be diminished; but there is usually enough gas stored to last for some time. However, wben the stored gas has dwindled to a low degree, the flow of acid will continue as the process is repeated. Should a greater pressure be built up in bottles C than is normally expected, forcing all the water into bottles D, the excess gas will escape through the hood. But if the manometer tube were too short, the apparatus would not function as desired. It would not store any residual gas. Instead, the gas may "backfire" into the acid bottle, and the flow of acid not start until the pressure system is practically nil. The residue in bottle B is drained from time to time, and the acid bottle recharged. All the rubber connections y e made of high-quality tubing coated with a thin. film of paraffin. This is done by immersing the tubing in hot paraffin for a few minutes. The corks are also coated with paraffin and securely fastened with wire and sealed with sealing wax. A little paraffin is added to the sealing wax to decrease the brittleness. Fifty pounds of ferrous sulfide generate sufficient gas to serve a qualitative class of forty students for one semester. The apparatus should be built in a hood to eliminate any escaping gas. If proper care is given the apparatus, there is practically no odor.
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A LECTURE EXPERIMENT FOR DISTINGUISHING LEVULOSE FROM GLUCOSE the past six years, has given good results. Each year EMIL W. ZMACZYNSKI it is rebuilt by a student assistant of the department. The gas is generated by means of the action of comPedagogic Institute of Saratoff, Saratoff, U. S. S. R. mercial hydrochloric acid on sticks of ferrous sulfide. Excellent results may be obtained by using one part of acid to five parts of water. The acid is stored in TO DISTINGUISH levulose from glucose Scliwanbottle A (see diagram) and the ferrous sulfide in bottle off's reaction1 is commonly recommended. The r e B. When the stopcock G is opened, the acid flows action consists of heating the sugar solution with into bottle B, and releases the hydrogen sulfide. The Ber., 20, 181 (1882). .gas is collected in bottles C, and the water is forced TL~ANOPF, 399
