Note: This article first appeared in the 23 November 2001issue of The Amateur Scientists E-Bulletin.
Adapted from A Thousand and One Formulas by Sidney Gernsback
Among the automatic gas generators on the market there are few within reach of the average experimenter. To meet this condition, Prof. C. D. Dilts has recently developed a generator which may be easily and cheaply constructed. In experimenting with qualitative analysis a constant supply of hydrogen sulfide is essential. This generator, being self-regulating, will furnish a constant flow of hydrogen sulfide, carbon dioxide, or hydrogen. The principle of operation is the same as that of the well-known Kipp generator, namely that when the gas formed is not allowed to escape the solid material is automatically raised out of the liquid, but when the pressure is relieved the solid substance is lowered into the liquid, and the generator begins to function. As will be seen in the drawing, the four parts are: first, a glass jar or container; second, a bottle of slightly smaller diameter, with the bottom removed, and fitted with a stopcock in the top; third, a lead basket for holding the solid material and fourth, a small wash bottle.
The glass jar may be easily made by cutting off the top of a large bottle. There are many methods which may be employed in removing the bell of the bottle, but by far the best and surest is the one described below.
Several long strips of newspaper, about an inch wide, should be soaked in water and wound about the bottle in two bands at the place where it is desired to break the bottle. About a quarter of an inch should be left between the two bands. The bottle should then be slowly revolved with the hands, allowing a blow-pipe flame to play upon the exposed part between the bands. When this portion is heated sufficiently the application of a drop of water will cause the glass to be evenly broken. The edges should then be smoothed on a soft grindstone. The bottom of the smaller bottle is removed in the same manner.
The sheet lead for the basket may be procured at any plumbing shop. It may be easily bent to the required shape, leaving small holes in the bottom to allow the acid to enter. The basket is suspended by means of a closed piece of glass tubing, bent to form a hook, which runs through the two-hole stopper. The delivery tube from the bottle may be fitted either with a glass stop-cock or with rubber tubing and metal pinch-cock. Although not absolutely necessary, a wash bottle is a desirable addition to the generator, as it not only steadies the flow but cleans and purifies the gas.
The apparatus should now be assembled as is illustrated in the drawing. The solid material, such as iron sulfide (when H2S is desired) is placed in the lead basket and the dilute acid in the glass jar. When the smaller bottle is placed in the jar the acid, reacting with the iron sulfide, engenders a flow of H2S which forces the acid out of the basket if the stop-cock is closed. When the stop-cock is opened, the gas escapes and allows the acid to touch the iron sulfide, again causing the formation of H2S. Thus gas is always easily procurable without waste of material.