Mr. Davy on a new Gaseous Compound of Carbon and Hydrogen. 8 1 



regarded as a new combination. I purpose, at my earliest leisure, to make the 

 black substance to which I have referred, the subject of a separate communication 

 to the Academy, and to confine myself at present chiefly to the properties and 

 composition of the new gas. ; '-v ' ' 



MODE OF OBTAINING THE NEW GAS. 



The new gas was obtained by the action of pure water, (previously boiled for 

 some time,) on the black substance. It was collected in a tube over water, by 

 nearly filling the tube with dry mercury, putting into it a few lumps of the black 

 substance, pressing the thumb closely to the top of the tube, so as to exclude any 

 air, and inverting the tube in water ; then by a slight relaxation of the thumb, 

 the mercury was allowed gradually to descend, and the water coming in contact 

 with the black substance, the gas was readily generated. In cases where the gas 

 was collected over mercury, a few lumps of the black substance were placed at 

 the bottom of a tube, which was held in an oblique position, and cautiously filled 

 with mercury, so as to retain the black substance at or near the bottom of the 

 tube, which, being then inverted in mercury, a little pure water was let up into 

 the tube, when the gas was of course readily produced. 



In every instance in which the new gas was collected, whether over water or 

 mercury, some carbonaceous matter (apparently liberated during the generation 

 of the gas) adhered to the sides of the tubes, and surface of the water or mercury ; 

 so that previous transfer to another receiver was necessary, before the gas could 

 be used. Sometimes I operated on the new gas over water, at other times over 

 mercury. In the subsequent experiments on its analysis, it was first collected 

 over water in one tube, then transferred to another, which being filled with it, 

 was removed to a mercurial apparatus, and dried first by means of bibulous paper, 

 then let up into a dry receiver, and exposed for some days to the action of 

 chloride of calcium, which had been previously heated to redness. Six grains of 

 the black substance, I found, in one instance, yielded about two cubic inches of 

 the new gas. 



VOL. XVIII. M 



