GAS GENERATORS RALPH J. BROOKS State Teachers College, Whitewater, W i w &
ONE of the most troublesome problems of the small college or high school is an inexpensive yet adequate supply of the common gases, namely: carbon dioxide, hydrogen, and hydrogen sulfide. Heretofore, the most universal device used to procure this supply has been the Kipps generator. This apparatus is not available to many smaU schools because its cost is prohibitive. unsatisfactorv to larmr schools because of the . - . ~ and , quantity of gas generated and trouble of recharging. These diiculties the author has overcome. The author found he could coustruct an apparatus sdciently large to take fifty pounds of ferrous sulfide and make enough hydrogen sulfide to supply a class of thirty doing qualitative analysis for halfa semester. The apparatus consists of two tripods, two five-gallon acid bottles, two rubber stoppers, a few short lengths of glass tubing, a few feet of rubber tubing, and two pinch clamps. These articles are found in almost all laboratories. The sketch given is almost self-explanatory. The apparatus consists of Chambers A and B which are two bottles, which may be any convenient size. In Chamber A is olaced the solid reacting snbstance, which in our case was ferrous sulfide. A two-hole rubber stopper is fitted to the bottle. Iuserted in one hole of the rubber stopper is an L glass tubing extending almost to the bottom of the bottle and protruding out through the stopper. To the glass tubing is attached a long piece of rubber tubing fitted with a pinch clamp. Into the other hole of the rubber stopper is inserted the short end of an L glass tubing adjusted so the glass- tubing just passes through the stopper. In Chamber B a three-hole rubber stopper is fitted with similar glass tubing as used in A; through the third hole of the stopper a short length of glass
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tubing is passed to which is attached a short length of rubber tubing fitted with a pinch clamp. The long piece of glass tubing which extends near the bottom of the bottle is always left open so that the air may freely pass in and out of Chamber B when the apparatus is in operation. The purpose of the small outlet marked c' is to fill Chamber B with new acid or drain off the spent acid as needed. The portion of the apparatus marked ..
d connecting Chambers A and B should consist of two pieces of glass tubing connected by means of a short piece of rubber tubing to prevent the apparatus from being too rigid. Chamber B should be charged with dilute hydrochloric or sulfuric acid through tube c'. To operate the apparatus open pinch clamp c and gas will flow from the apparatus and on the closing of clamp c the gas generates in Chamber A, forces the liquid back into Compartment B, and the chemical reaction ceases. The apparatus is then charged with the desired gas and ready for use.
