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ON THE USE OF COAL GAS AS A SOURCE OF HEAT FOR THE LABORATORY. BY EDWARD N. KENT.
Having recently fitted up a new laboratory in which I have introduced coal gas as a source of heat, I have thought a description of the apparatus and manner of using it, would be interesting to chemists and pharmaceutists, as it has not been very generally applied to this purpose as yet in this country, although in England, where alcohol is dear, it has long been used as a substitute.
In the use of coal gas as a source of heat, the principal difficulty to be avoided, is its tendency to smoke; this I have accomplished in a variety of ways. The ordinary argand gas burner, fixed permanently upon a branch pipe passing up through the table, is one of the cheapest, and a convenient arrangement for many purposes, and to prevent smoke, a tall glass chimney, or a short sheet iron chimney, with every other hole in the burner plugged, so as to make separate and distinct jets for the air to pass through, is all that is necessary. A tripod or sheet iron cylinder, for supporting vessels over the flame, is an indispensable addition to this burner. There is one objection to this form of apparatus, which is, that it is fixed, and cannot be moved about like a lamp. To avoid this inconvenience, I have had a number of burners constructed in different ways, and connected with flexible tubes, so as to admit of a change of position, to any place within the length of the tube.
Fig. 1.
Figure 1, is a gas burner designed as a substitute for the Rose Lamp, and when connected to the gas pipe by means of a flexible tube, answers every purpose of that excellent lamp without being liable to the danger of catching fire, or to the necessity of replenishing during an operation, as is the case with most alcohol lamps. The above arrangement consists of an ordinary argand gas burner, with every other hole plugged, fixed to an arm with a socket and {297} thumb screw, by means of which it can be raised to any height on the rod attached to a moveable wooden foot. The lower part of the burner is provided with a screw to which the flexible tube is attached, by means of a Hare’s gallows screw connector. The other end of the flexible tube should be provided with a stopcock, at its union with the fixed gas pipes for regulating the supply of the gas. Above the burner is a moveable ring, with socket and thumb screw, for supporting retorts, flasks, etc., at any desired height. A glass chimney is represented in the figure, but this may be replaced with a short sheet iron chimney, when part of the holes in the burner have been plugged as before mentioned. The above burner is well adapted for use with the wire gauze chimney, as the moveable ring with the addition of a wire tripod, answers as a support for a platina crucible. To insure a perfect combustion of the mixture of gas and air, I find that the sheet iron cylinder should be about ten inches high and two inches diameter. Over such a cylinder, with the upper end covered with wire gauze, it is an easy matter to fuse carbonate of soda, or other substance requiring a bright red heat. When the combustion is perfect with the above cylinder, the flame is of a pale blueish white color, like that of a solid flame from alcohol but much hotter. With the addition of a small conical chimney of sheet iron, placed over the mixed gas-burner, so as to bring the blue flame to a smaller compass, I find it a very convenient and powerful flame for bending glass tubes, by which tubes of any diameter, or the neck of a retort, may be easily softened and bent.
Fig. 2.