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different substances, for the purpose of obtaining inflammable gases, to afford light by their combustion. Some sorts of coal give only a poor gas, burning with a pale blue light, and with only a feeble illumination; while from other kinds of coal, the gas gives a rich brilliant light, hardly surpassed by any thing. I believe the Cannel coal is generally used in Great Britain: I have found some specimens of the Richmond coal (Virginia) answer very well; but, few substances which I have tried, afford a richer gas than walnut meats (as they are commonly called), and even the whole of the walnut (shell and all) answers very well, and a quart of walnuts will afford a barrel of gas. Walnuts are too dear in the maritime parts of New Eng. land to be substituted for coal, but the hint might be of advantage in some parts of this country, where walnuts abound, and coal is dear. The light from the inflammable gases, when of a good quality, is remarkably steady and uniform; as there is no wick, do snuffing is necessary; and workmen, in manu. factories lighted in this manner, are not interrupted as they commonly are in trimming their lamps.or snuffing their candles; the light does not become dim occasionally, as that from lamps and candles does; nothing falls from the light, or can possibly fly from it to kindle cotton, linen, or other combustible substances, which abound in many manufactories; and, as the gas light is necessarily confined to the spot where it is used, and as any particular light can be instantly extinguished by simply turning the key of a stop-cock comected with that particular tube, or the whole can be put out by turning the key of the main tube, the security against fire becomes as complete as the nature of combustion will probably ever permit.

It is a circumstance also of no small importance, that a workman may regulate the quantity of light which he wishes, by properly adjusting the key of the stop-cock; if the workman wishes to go away for a time, and still does not choose to extinguish his light, he may, by cautiously closing the key of the stop-cock, reduce the flame to a mere point, which like a little

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brilliant star, rests on the orifice of the tube, and will remain so for hours, with scarcely a perceptible consumption of gas; and when the key is again turned back, the light blazes out anew, with its former brilliancy.

Much more might be written on this subject, upon which, sir, you have requested my opinion, but perhaps it is not necessary. If apparatus, materials, and attendance, are not materially more expensive in this country than in England, the gas lights can, and without doubt will be advantageously introduced into our manufactories. I wish you success in your laudable efforts to make this useful and comparatively novel subject known to our countrymen, who are certainly inferior to the people of no country in ingenuity, resource, and enterprise, although they often are, in that perfect knowledge of the subjects to which they turn their attention; which, in older countries, results from a more minute division of labour and employment, and of course a more complete devotion to one object.

I remain, sir, respectfully,
Your most obedient servant,

BENJAMIN SILLIMAN.

References to the Plate representing Melville's Improved Gas Apparatus for lighting manufactories, &c. with gas lights, produced from pit or stone coal.

FIG. I. AAA. The floor and part of the structure of the gasometer

house. B. A furnace in which the retort is set. c. The door of the furnace where the fire is placed. D. The ashes hole. E. The damper, or register to regulate the draft of the furnace. F. A cast iron retort (with the door fixed on) in which the

coal is put to produce the gas. . G. The condenser and bath.

H. A pipe which conducts the gas from the retort to the con

denser and bath, where it passes several times through

water, by which it is washed and purified. 1. A cistern set in the ground and kept filled with water by

means of an aqueduct, the water from which passes through

the bath, to a drain from the gasometer house. K. 'The gasometer, or reservoir, which is suspended in the

cistern of water, by a rope or chain leading over sheaves 'to.

a balance. L. A pipe which conducts the gas from the condenser, through

the water in the cistern, to the gasometer, where it is re

served for use. M. A stop-cock to let off the gas until it becomes inflammable,

and to burn it from, when the gasometer is full, to prevent

its escaping underneath. N. A balance of weights, to hold the gasometer in suspension and (by taking one or more of the weights off) to give force

gas
when

necessary. Q. A pipe which conducts the gas from the gasometer house

to the apartments where the lights are wanted; where it issues from the burners when vent is given to it, and on the application of a taper will burn with a brilliant flame with out smell or smoke. The burners are fitted with keys by which the flames may be regulated, to give more or less light, or instantly extinguished, which operation may be performed on the whole at once, by means of a single key in the main tube.

FIG. II. p. The form of the burner from which the gas issues, with the

tube and glass, and key to regulate the flame, on a larger scale.

to the

Specification of the mode of operation with Melville's Ime proved Gas Apparatus for lighting Manufactories, &c., with gas lights.

A quantity of coal ia proportion to the number of lights re

quired, must be placed in the retort, and the door screwed on and luted tight with a lute of clay and sand; this done, a strong heat being applied by means of a fire kept up in the furnace, hydrogenous gas, or inflammable air, will be driven out of the coal confined in the retort, and forced through the water in the bath in which the condenser is immersed; by passing through the water, the bituminous matter, which is a component part of the coal, is separated from the gas, which is washed and purified. From the condenser, the purified gas is passed by a pipe through the water in the cistern, to the gasometer, where it may be reserved for use. As the gas passes in, the gasometer will be raised up until it is filled; when full, (to prevent the escape of the gas underneath, and the smell which it occasions when it issues without burning,) it may be burned from the cock on the pipe which leads from the condenser to the gasometer. When the lights are required, by taking a weight off the balance, the gasometer bears with so much the greater force on the volume of gas contained in it, by which it will be propelled through the pipes to any distance and in any direction to the burners, which are situated where the lights are wanted. Immediately on the issuing of the gas from the aperture of the burner, and coming in contact with the oxygenous gas of the atmospheric air, it will take flame on the application of a taper, and burn with a brilliant light, without smell or smoke, as long as there is any gas in the gasometer.

The burners are fitted with keys by which each separate flame may be regulated to give more or less light at pleasure, or be instantaneously extinguished; and the whole (be there ever so many) may be regulated as to the size of the flame, or they may be instantaneously extinguished by turning the key in the main tube.

The quantity of coal required for any given number of lights will vary with its quality; the usual quantity is about forty pounds for fifty flames, equal to that of a moulded candle of six to the pound, to burn three hours. Two pecks of coal weighing forty pounds, put into the retort, will leave a resi

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Melvilles Patent improved Gas - apparatus

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