190 ANNUAL OF SCIENTIFIC DISCOVERT. 



procuring this gas by passing hydrogen between the carbon electrodes 

 of a powerful battery. Dr. Oddling has since shown that the same 

 gas may be produced by mixing carbonic oxide with an equal volume 

 of light carburetted hydrogen, and exposing the mixture in a porcelain 

 tube to an intense heat. Still more recently, Mr. Siemnes has de- 

 tected the same gas in the highly-heated regenerators of his furnaces, 

 and there is now every reason to believe that the new gas will become 

 practically available for illuminating purposes. Thus it is that dis- 

 coveries which in the first instance interest the philosopher only, almost 

 invariably initiate a rapid series -of steps leading to results of great 

 practical importance to mankind." 



A correspondent of the N. Y. Tribune, under date of Oct. 24, 1863, 

 also describes some improvements in the manufacture of gas, recently 

 effected by Dr. W. Elmer, of New York. These improvements, he 

 says, are based upon the general fact that all the materials it is desir- 

 able to convert into illuminating gases have in them an excess of carbon 

 over even the requirements of the richest gas that can be ordinarily 

 burned ; still more, over what the common or coal-gas process can 

 convert. All those materials have in them some hydrogen, but none of 

 them enough to render all their carbon available. In the first place, 

 then, the new method obtains from an extraneous source an abundant 

 supply of the simple element hydrogen, adequate to the needs of any 

 of the crude materials operated on ; and it regulates this supply so as 

 to afford to each of the sorts of materials just the percentage of hydro- 

 gen required, in view of its composition and that of the gas to be gen- 

 erated. 



This additional supply of hydrogen, it is proposed to obtain, by 

 decomposing the vapor of water, by bringing steam in contact with 

 metallic zinc at a high temperature, oxide of zinc and free hydrogen 

 being the resultant products. This oxide of zinc, in the form of zinc- 

 white, it is claimed, has a higher value as a pigment than the metallic 

 zinc originally employed ; and, therefore, the cost of hydrogen, liberated 

 through its agency, is comparatively trifling. The hydrogen, as above 

 produced, is, by means of an appropriate apparatus, intermixed, at or 

 near the moment of its liberation, with hydro-carbon vapors containing 

 an excess of carbon, and obtained by the distillation of bituminous 

 coals, shales, peat, resin, or other similar substances ; the effect of which, 

 it is stated, is to produce a mixture containing any desired percentage 

 of carbon, or such a one as will have the greatest illuminating property. 

 Illuminating gas, thus produced, is claimed to be more economical in 

 its production and uses than that manufactured by any other process. 



Purifying Gas. An important improvement in purifying coal-gas, 

 having for its main object the removal of sulphur, has been lately made 

 by the Rev. Mr. Bowditch, of England. All gas that is purified in the 

 common way contains certain quantities of sulphur in the form of 

 bisulphide of carbon, and probably also in that of sulphur-organic com- 

 pounds. The gas may be passed in the usual manner over lime or the 

 peroxide of iron ; but, this operation does not, in the slightest degree, 

 affect the sulphur compounds in question. During the combustion of 

 the gas, however, the sulphur is converted into sulphurous acid, which 

 diffuses itself in the apartment in which it is burned, and a great deal 

 of the discomfort of which many complain in the use of gas is due to 



