hydrogen gas will send up such a vapour; and that he has been informed, that when oil-gas was condensed in Gordon's lamp, it deposited a portion of highly volatile oil.
A writer in the 'Annals of Philosophy,' N. S. iii. 37, has deduced from Dr. Henry's experiments, that the substance, the existence of which was pointed out by Mr. Dalton, was not a new gas sui generis, "but a modification of olefiant gas, constituted of the same elements as that fluid, and in the same proportions; with this only difference, that the compound atoms are triple instead of double:" and Dr Thomson has adopted this opinion in his 'Principles of Chemistry' This, I believe, is the first time that two gaseous compounds have been supposed to exist, differing from each other in nothing but density; and though the proportion of 3 to 2 is not confirmed, yet the more important part of the statement is, by the existence of the compound described at page 163; which, though composed of carbon and hydrogen in the same proportion as in olefiant gas, is of double the density[1]
It is evident that the vapour observed by Mr. Dalton and
- ↑
In reference to the existence of bodies composed of the same elements and in the same proportions, but differing in their qualities, it may be observed, that now we are taught to look for them, they will probably multiply upon us. I had occasion formerly to describe a compound of olefiant gas and iodine (Phil. Trans. cxi. 72), which upon analysis yielded one proportional of iodine, two proportionals of carbon, and two of hydrogen (Quarterly Journal, 429). M. Serrulas, by the action of potassium upon an alcoholic solution of iodine, obtained a compound decidedly different from the preceding in its properties; yet when analysed, it yielded the same elements in the same proportions (Ann. de Chimie, xx. 245; xxii. 172).
Again: MM. Liebig and Gay-Lussac, after an elaborate and beautiful investigation of the nature of fulminating compounds of silver, mercury, &c., were led to the conclusion that they were salts, containing a new acid, and owed their explosive powers to the facility with which the elements of this acid separated from each other (Annales de Chimie, xxiv. 294; xxv. 285). The acid itself, being composed of one proportional of oxygen, one of nitrogen, and two of carbon, is equivalent to a proportional of oxygen + a proportional of cyanogen, and is therefore considered as a true cyanic acid. But M. Wiihler, by deflagrating together a mixture of ferroprussiate of potash and nitre, has formed a salt, which, according to his analysis, is a true cyanate of potash. The acid consists of one proportional of oxygen, one of nitrogen, and two of carbon. It may be transferred to various other bases; as the earths, the oxides of lead, silver, &c.; but the salts formed have nothing in common with
