14 PNEUMATO-CHEMICAL APPARATUS. 



gilt. The best material for the lamp-furnace is 

 brass lackered, and the lamp should be of tin ja- 

 panned. The apparatus constructed in this man- 

 ner has an extremely elegant appearance, and is 

 found to answer perfectly well for a variety of che- 

 mical operations. 



When the gas to be procured is absorbable by 

 water, quicksilver is used instead of water ; and, 

 as it is very expensive, a smaller vessel is neces- 

 sary, which must be made of some material not 

 acted upon by quicksilver, as wood or stone ; and 

 it must be sufficiently strong to resist the great 

 weight and pressure of the quicksilver. It is usually 

 cut out of a solid block of wood, or marble, or 

 made very strong of mahogany, and varnished over, 

 to make it perfectly tight. 



A small glass vessel, capable of containing an 

 ounce measure, is used for measuring gases ; for 

 if this phial be successively filled, and inverted un- 

 der a large jar, we may thereby throw into that jar 

 any required quantity of an elastic fluid, or as many 

 measures of one elastic fluid, and as many of ano- 

 ther, as we please. 



G (Fig. 7.), represents a tube for receiving a 

 mixture of gases that are to be exploded by the 

 electric spark. It is a very strong glass tube, closed 

 at one end, and having a scale upon it, cut with a 

 diamond. Near the closed end two wires pass 

 through the glass, and almost touch each other, 

 but not quite ; they are cemented in, so as to make 

 the holes air-tight. When this graduated tube is 

 filled with the fluid in the trough, and inverted 

 upon the shelf, certain measures of the gases to be 

 exploded are introduced in the usual way. If thus 

 the interval between the two wires be made a part 

 of the electric circuit, by fastening chains con- 



