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that the light was also whiter, more brilliant, and burnt more steadily. He acknowledged, however, that his attention had been chiefly directed to determine the specific gravity and relative intensity of the two gases, that he had never mixed much, and only occasionally, with the manufacturing of them, and had not made many experiments on the subject;" in short, he deemed his experiments as "entirely scientific," and therefore the tenour of his evidence consisted rather of inferences and opinions than a detail of facts which had come under his own observation.*

As the "comparative advantages of oil and coal gas" were now become the subject of legislative consideration, it afforded a peculiar opportunity for ascertaining how far those who had been most prominent in descanting upon the merits of oil gas, and urging its "superiorities" upon the public notice, had qualified themselves, by actual experiments and observation, for the task which they had undertaken. It will also be re

* Mr. Faraday, and also several others, were questioned respecting the specific gravity of oil and coal gas, and as this constitutes an important property, by indicating, in a great measure, its illuminating power, when the gases are pure, the different statements are comprised in one table in a future part of the narrative.

collected that attention was earnestly solicited to its striking and intrinsic advantages in 1819, by those whose professed object was merely to promote the progress of improvement by communicating and recording the useful discoveries which contributed to enlighten and to benefit society; hence, the evidence of those individuals who had either written, or countenanced by their publication, the articles in which the qualities of oil gas had been so exuberantly expatiated upon, became an object of no ordinary curiosity and interest; and the inquiry was particularly useful in this respect, because it enabled the public to form a more accurate estimate of the correctness of the information contained in them.

CHAPTER XVII.

ABSTRACT OF THE EVIDENCE OF MR. BRANDE, MR. RICARDO, &c., ON THE LONDON AND

WESTMINSTER OIL-GAS BILL.

That the projectors of the London and Westminster Oil-Gas Company should select such persons only to give evidence as they knew to be decidedly favourable to their scheme, was naturally to be expected. Mr. T. W. Brande, the Profes

sor of Chemistry at the Royal Institution, and Secretary to the Royal Society, had been the first and most conspicuous advocate of oil gas;* of course he seemed to be peculiarly adapted to render them essential service in the attainment of their object, and was adduced to be examined. The component parts of coal gas, before it has been purified, were the first point of this inquiry in which he was concerned, and he stated them to "consist chiefly (according to his view of the subject) of carburetted hydrogen, pure hydrogen, carbonic acid, a portion of carbonic oxide, sulphuretted hydrogen, and certain other substances held in solution as vapours ;" that "the only substance calculated to give light, after the gas has been purified in the usual way, is carburetted hydrogen;" and that "tar and a compound containing ammonia, which he believes to be hydro-sulphuret of ammonia and water," were the substances contained in it in the form of vapour. The sulphuretted hydrogen, hydrosulphuret of ammonia, and some other compound of sulphur, which exists in purified coal gas, (and which he believed to be sulphuret of carbon,) were the substances which he deemed to be "offensive and injurious." He stated, that he had, in vain, endeavoured to separate that portion of

* Journal of Science and the Arts, 1819.

sulphur which remains in purified gas; and that he "had seen copper pipes exceedingly corroded by the sulphuretted hydrogen and other impurities of coal gas." But being questioned as to the time when he had observed the latter circumstance, he replied, that the pipe which he first saw in that state came from Carlton House about the year 1815 or 1816; afterwards at Apothecaries' Hall the copper pipes were stopped up, and he found them to contain a bluish grey powder; that he had examined some of the pipes used by the coal-gas companies which contained the same substances, and that he had similar pipes put into his hands by Mr. Taylor a few days ago. But all the other impurities of which he spoke had come under his observation at Apothecaries' Hall, where they made and purified their own gas; that he had passed the gas through cream of lime, until it produced no further effect upon the lime; besides, he had passed carburetted hydrogen and sulphuretted hydrogen together

* From various little circumstances which occurred during this investigation, it might have been inferred that the projectors of the oil-gas scheme imagined that neither the Committee nor the public were aware of the great improvements in the purification of coal gas during the few previous years.

through a red-hot tube, and found sulphuret of carbon the result; therefore he concluded that sulphuret of carbon was a most mischievous ingredient, and knowing how difficult it is to get rid of it, he had endeavoured to purify gas for use, but could never succeed. He confessed that he had never endeavoured to discover by any experiments what proportion of sulphuret of carbon existed in coal gas, but he believed that it could be purified from every other noxious ingredient excepting that. However, he had endured the gas made at Apothecaries' Hall for nearly three years without making any comparison with or trying any other coal gas; and although a number of experiments on its purification had been made under his direction, he had never been present at more than five or six, which were made at Apothecaries' Hall about the year 1818. The change from coal to oil gas was effected at that place in 1819 or 1820, and since that time he had "meddled very little with coal gas;" but he stated as the reason for the change, that "the different rooms smelt of coal gas so much during the daytime, they were frequently uninhabitable, and at night, while the gas was burning, there was a strong smell of sulphurous acid."*

* Were not these inconveniencies to be attributed to

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