CHEMICAL SCIENCE. 199 



will furnish about one hundred and seventy gallons of carbonic acid 

 gas ; and all this at a cost of about eighteen cents ! 



There is no danger of explosion, as in the ordinary copper appara- 

 tus, because the pressure can never rise sufficiently high, and the 

 evolution of gas can be stopped at any moment by withdrawing the 

 sliding rod which dipped the marble into the acid. Moreover, if de- 

 sired, though not imminently necessary, a safety valve, as well as a 

 pressure-gauge, may be put on. The beautiful simplicity of the appa- 

 ratus, its safety, its easy management by the most ignorant person, 

 and, above all, its low price, making it accessible to all classes, are the 

 best recommendations to the public at large. 



By means of this cheap gas apparatus, lager beer can not only be 

 kept continually fresh and impregnated with carbonic acid gas, but 

 also, by a proper arrangement of tubes, forced up by it, fresh and 

 sparkling, to the last drop. The same may be applied to soda water, 

 lemonade, wine, and other beverages. 



CHLORINE. 



A new mode of producing chlorine is due to the researches of M. 

 Laurens. It consists in decomposing chloride of copper by the action 

 of heat. The operation is conducted in the following manner : Chlo- 

 ride of copper is prepared in the usual manner, either by dissolving 

 oxide of copper or native carbonate of copper in hydrochloric acid, 

 or by the double decomposition of sulphate of copper and chlo- 

 ride of barium. The solution of chloride of copper obtained is 

 evaporated and submitted to crystallization, then the crystalline mass 

 is mixed with sand and perfectly dried (probably in a reverberatory 

 furnace). The dried mixture is introduced into retorts similar to 

 those employed in the fabrication of gas ; if these retorts are of 

 iron, they are lined with a coating formed of a mixture of clay and 

 carbon, to isolate the metals. The chloride, heated strongly, is 

 decomposed into chlorine and protochloride. The residue of the 

 preparation of chlorine, i. e., the protochloride, is not lost. It can 

 be again converted into chloride by the oxidizing action of the at- 

 mosphere in presence of hydrochloric acid. Having thus obtained the 

 regenerated chloride, the operation is repeated as before described, 

 and the circuit may be renewed indefinitely. 



NEW PROCESS FOR MAKING OXYGEN. 



A new and cheap process for making oxygen gas has been devised 

 by Mr. I. Webster, of London, and a company has been organized to 

 introduce the invention. The materials used are nitrate of soda and 

 crude oxide of zinc, mixed together in the proportion of ten pounds 

 of the former to twenty pounds of the latter. The ingredients, thor- 

 oughly dried, are heated in an iron retort to dull redness, when a 

 large quantity of oxygen is speedily given off, mixed, however, with 

 nitrogen, to the extent of forty-one per cent. The cost of the oxy- 

 gen thus obtained is said to be about one-fifth of that of other pro- 

 cesses ; and it is expected that the mixed product of oxygen and 

 nitrogen thus obtained will prove useful to augment the illuminating 

 power of coal gas, and in various metallurgical operations. 



