Illustrated Catalogue Of Magic Lanterns (after November 1889, probably 1890)

MCINTOSH BATTERY AND OPTICAL CO., CHICAGO, ILL., IT. S. A. 75 The accompanying cut will show the arrangement of the retort, wash bottle, and bag. An alcohol lamp is here shown, but a Bunsen burner, or any fire that will give sufficient heat, will do. A good heat should be applied at first, but as the gas begins to pass over freely a more moderate heat is needed to make the gas flow with regularity. If, however, all heat be removed before the retort be disconnected with the wash bottle, water may be sucked back into the retort and cause an explosion. P represents our copper retort fitted at the top with a two inch ground stopper T, that acts as a safety-valve when the pressure becomes too great. (When a sheet-iron retort is used, the top is luted on with plaster of Paris ; it dries hard in a few mo- ments, and is then ready for making the gas.) P is a metal pipe, ter- minating in a brass nipple for connection with rubber pipe A from the wash bottle W. The wash bottle has two metal pipes soldered in its cover; the longer one is to be connected with the retort, and through it the newly made gas passes through the water to wash out the particles that are carried over with it, and which, if left in the gas, would be driven into the jet and prevent the flow of gases. The shorter tube conveys the gas from the upper part of the bottle through the rubber pipe B and stop cock C into the bag. It is better, if pos- sible, to place the bag on a table or some place higher than the wash bottle, so as to avoid as much as possible any water being carried over by the rapid flow of gas, as any dampness in connection with the oxygen gas soon rots the bag. Chlorine gas is also very injurious to the bag, and to prevent its being carried over with the oxygen, add a few crystals of common washing soda (sal soda) to the water in the wash bottle. Precautions. —Accidents have happened in making oxygen, but they are invariably due to gross carelessness. No one who has not some knowledge of chemistry, should undertake to make gases without reading and fully understanding the steps herein described. The chlorate of potash and manganese should be examined for small bits of straw, sticks, or other foreign substances. Practically the only danger is lest soot or charcoal be mixed with the samples. Never allow bystanders to take a part in making the gas. We have known an explosion caused by a curious spectator who pinched the rubber tube between the wash bottle and the bag while the gas was being rapidly made, the sudden check in the flow of gas forced water back into the retort. If by any accident the retort should fall off the fire, do not replace until certain that the neck of the retort and pipes are clean, as the charge may choke the outlets and cause an explosion. In making oxygen gas, many persons put their iron or copper retorts away with the spent charge left in, either in a dry state or wet. This slowly destroys the metal. The retort should, when somewhat cool, be half filled with water (either cold or warm), which will dis- solve the charge; wash this out until entirely cleaned. Now place the retort upon the gas or fire until all dampness has dried out, and it can then be put away until again required. This will make the retort last double the time. The charge should not in any case be knocked out with an iron rod. Should you wish to know if a retort be unfit for further use, you