which I have been able to procure in the market, I have always found burns with a more or less blue lambent or with a yellow flame,-a sign that the coke is not fully deprived of gas and other volatile subjects, which it ought to be; that it still contains some bituminous matter, which, when the coke is again heated, is expelled and yields the flame.

Q. Is there any observation to the same point to be made upon any of the other products that you have been speaking of, with respect to their comparative merit with those produced in the common way?-A. I have seen tar, in commerce, said to be obtained from coals; but the tar differs materially from the tar which is obtained during the process of the production of gas-light; the tar which I have met with in the market has less of an adhesive quality, and I believe that quality is essential to tar.

Q. Can that tar be used cold for any purposes?—A. It may, for it is more fluid than the vegetable tar, and its adhesive quality certainly is greater.

Q. In the production of coke and of tar, under the process which you describe, may the public be supplied cheaper with either of those articles?-A. The public certainly may, for if the gas be alone employed as a substitute for oil or candles, this alone will compensate for the expense that is incurred in obtaining the other articles; besides this, as the quantity of coke that is to be obtained from a given quantity of coal, is in favour at least fifty per cent. in bulk, to that of the coal originally employed, and as coke is sold like coal, by measure, this article of course is procured gratis; besides all this, a considerable quantity of tar, of ammoniacal liquor, of asphaltum, and of essential oil, all

articles that may be brought to market, are procured at the same time.

Q. Are the oil, tar, pitch, asphaltum, and the essential oil, which are obtained from coal, as good as those articles that are imported into this country ?-A. They are, and some of them are superior to those that come from abroad.

Q. Does the use of ammoniacal liquor in dyeing, prevent the stain which arises from vegetable acids ? —A. Articles died with the ammoniacal liquor are not liable to be stained by those agencies which effect a change upon articles dyed in the common way.

Q. Can you state in what proportion these results are produced from a chaldrom of coals?-A. From reiterated experiments that I have lately made I am enabled to say, that a hundred weight of Newcastle coals produces from two hundred and fifty to three hundred cubic feet of gas; and with regard to the light that is obtained from the combustion of this quantity of gas I am enabled to state, that nineteen cubic feet of gas, if applied to the purpose of illumination, is equal to a pound of tallow candles; that is to say, if a tallow candle, six to the pound, be set up and lit, and if it be suffered to burn for an hour and weighed after that time, it will be found to have lost 180 grains; therefore 180 grains of tallow are necessarily consumed in the combustion of a candle during the time of one hour. If I make a gas light of equal intensity to that of the tallow candle, I find that half a cubic foot of gas is requisite for the same period of time, and to give the same intensity of light; therefore, from this statement it will become obvious that nineteen cubic feet of gas are equal to one pound of tallow candles, provided they were set up and burnt out

one after another, that is to say, nineteen cubic feet of gas are demanded to give a quantity of light equal in duration of time and in illuminating power to one pound of tallow candles, six to the pound. I have stated already that a hundred weight of coal produces from 250 to 300 cubic feet of gas; therefore, from this statement the value of gaslight, with regard to intensity and duration of time, may be learned when compared to that of the light of candles.

A hundred pounds of coal produces from four to five pounds of tar upon an average; this tar is worth from 33s. to 36s. a barrel at present. A chaldron of coals produces sixty pounds of pitch, which is worth about three-pence halfpenny a pound; and a chaldron of coals has produced to me thirty-two pounds of essential oil; this I could sell at sixteen guineas a hundred weight. With regard to the quantity of asphaltum from one chaldron of coals, I obtained from twenty-eight to thirty-two pounds; this I could sell at 180s. the hundred weight; and the quantity of ammoniacal liquor amounts to one hundred and eighty pounds, that is, about eighteen gallons; and fourteen hundred weight of ammoniacal liquor produced half a hundred weight of carbonate of ammonia; this sells at about sixteen guineas the hundred weight; and fourteen hundred weight of ammoniacal liquor, if it be converted into muriate of ammonia, will produce a hundred weight of muriate of ammonia, which is worth fourteen guineas.

Q. What do you reckon the price of a hundred weight of coals?—A. I reckon a chaldron of coal at retail price 65s.; and I take a chaldron of coals to be about twentyeight hundred weight.

Q. Describe how pitch and asphaltum are produced?

A. The oil spoken of before is obtained by submitting the tar to a simple distillation; by continuing the same process, an additional quantity of essential oil of an inferior quality is produced, whilst the consistence of the tar becomes diminished, and then approaches to a state of pitch. By a further application of heat, and consequent subtraction of an additional quantity of oil, the pitch becomes converted into an asphaltum, which is to be purified in the usual

manner.

Q. Can bright colours be obtained from ammoniacal liquor? A. Yes; a most vivid red, orange, and yellow, and shades of those colours may be produced in the art of dyeing by means of the ammoniacal fluid.

MR. CLEGG'S OWN

(E.)

ACCOUNT OF HIS INVENTIONS.

EXTRACTED FROM A SMALL PAMPHLET, PUBLISHED BY HIM IN 1820.

He begins with a complaint that "most of the improvements which have originated with himself, and many of his inventions, have been pirated by others, and palmed upon the public as originating with themselves.”

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'My attention," he says, was first directed to the preparation of gas for the purposes of illumination in the year 1804. In 1805, I erected a gas apparatus at the cottonmill of Henry Lodge, Esq., near Halifax, which was the first in the kingdom. In 1806, I lighted his dwelling

bouse, where I first attempted to purify the gas by lime introduced into the tank in which the gasometer floated. In 1807, I lighted the manufactory of Messrs. T. and S. Knight, of Longsight, near Manchester. In 1809, I erected a gas apparatus in a large manufactory at Coventry, belonging to Mr. Harris, in which I introduced a paddle at the bottom of the tank, to agitate the lime. In 1811, I lighted a large manufactory at Dolphinholme, near Lancaster, by means of an apparatus similar to what I had erected at Coventry. In the same year, I erected an apparatus at Stoneyhurst College, Lancashire, where I introduced a lime machine, the first ever employed for that purpose: a machine which has been universally adopted, and which has rendered the introduction of gas practicable in any situation. In that year, also, I lighted a large cotton mill in Manchester, belonging to Mr. Greenway, where I first introduced the hydraulic pipes for insulating the retorts; a plan now in general use. In 1812, when the extensive cotton-mills belonging to Mr. Samuel Ashton and Brothers, at Hyde, near Stockport, were lighted, I introduced the lime machine and the hydraulic mains with increased effect. Here the 12-inch cylindrical retorts and improved mouth-pieces were first introduced. Here, also, I first attached to the gasometer the mechanism for regulating its specific gravity. In the same year, I lighted the premises of Mr. Akerman, in the Strand. In 1813, I undertook the direction of the different works belonging to the Chartered Gas-Light Company in London and Westminster, and during the four following years lighted a

* "Here I exhibited the portable lamps, by condensing the gas in a copper globe.”