You have no doubt been informed, at least thro the medium of News-papers, of Mr Peale’s complete success in illuminating his Museum with gas-lights, & presuming that it would not be uninteresting to you, I shall do myself the pleasure of giving you a description of his apparatus & process for generating & distributing the gas.

It is well known that any substance containing hydrogen will, by decomposition, produce an inflammable gas. Pure hydrogen gas is, perhaps, the most inflammable; but the light it produces is of a pale bluish colour. When combined with other inflammable substances, particularly carbon, the light is greatly improved. This carburetted hydrogen gas may be obtained, by heat alone, from various substances: bituminous pit-coal yields it in great abundance; but contaminated with sulphuretted hydrogen, & other matters which give it a very offensive smell, from which it is difficult to purify it. Mr Peale, after various unsatisfactory attempts with other substances, now makes use of pitch; from which, by simple distillation, he extracts a gas that gives a brilliant white light, perfectly free from any smell.

His apparatus consists of two cast iron matrasses, or Retorts, of a cylindrical form, each 36 inches long & 10 in diameter; placed horizontally, along-side of each other, in a close fire place of masonry; their ends, projecting a few inches beyond the masonry; being closed with plates of sheet copper, fastened on with screw & flanch. From one end of each issues a copper cyphon, thro which the gas is conveyed to a box of tin or copper, surrounded with water, where a small proportion of the gaseous product is condensed into an oily liquid of the colour & consistence of mollasses. In this oily substance,1 the pitch, after being melted, is dissolved, before it is introduced into the Retorts for distillation.

The gas, thus purified, is conveyed thro another tube into the gas-holder, without passing thro any portion of the water in which it is immersed; and from the gas-holder it is distributed, by small tin tubes, to the several burners.

But the enclosed sketch, drawn by Mr Peale, will, it is believed, give you a sufficiently clear idea of the whole process & apparatus

 

Explanation

 

AA		two Retorts of cast iron, inclosed in masonry
BB		Necks or tubes opening into the Retorts, to convey the dissolved pitch into the Retorts, previously made Red hot
CC		Funnels, furnished with
DD		Stop-cocks, for the purpose of admitting, by little & little, the dissolved pitch into the Retorts.
EE		Tubes to convey the gas from the Retorts, into
F		The condensing vessel, surrounded with
G		A box filled with water, which seldom requires renewing.
H		A tube, with its stop-cock, to convey the depurated gas from the condenser F to
I		The gas-holder, made of sheet copper, in a cylindrical form, its open mouth plunging downwards, into
J		A cistern containing water, & lined with thin sheet lead.
K		A distributing tube, conveying the gas to the burners.
L		A curvated tube to carry off the oily liquid from the condenser into
M		A square box lined with sheet lead; when full it runs over into
N		A box in which the oil & melted pitch are mixed together; & thence by
O		A hand-pump transferred to
P		The Reservoir from which the funnels are occasionally supplied.

 

Remarks

 

1.	The gas-holder may be made of any convenient form, whether square or cylindrical, at pleasure; and the cistern containing it may be a single vessel wholly filled with water, where the weight (as when sunk under ground) would be no inconvenience.
2.	To commence the process, before any oil is obtained, simple melted pitch may be used.
3.	The proportion of the oil obtained by condensation may be increased or diminished, according as more or less of the dissolved pitch is let into the Retort at a time
4.	A pot, in which the pitch is melted, is placed along-side of the Retorts, in the same masonry; and when the distillation of the gas is nearly finished, the fire is drawn from the Retorts, & placed under the pot.
5.	From the experience of some weeks, Mr Peale has furnished me with the following results.

	(1)		One barrel of pitch will produce 2000 cubic feet of gas, besides oil sufficient to dissolve an equal quantity of fresh pitch.
	(2)		After the Retorts are made red hot, they will generate 100 cubic feet of gas per hour.
	(3)		One cubic foot of gas, under a moderate pressure, will supply light for one hour, equal to that of 5 spermaceti candles2 of 4 to the pound.
	(4)		Every barrel of pitch will require 5 bushels of Stone coal, & 4 of wood coal to generate the gas.
	(5)		Mr Peale has two gas-holders, one containing about 100 cubic feet & the other about 300
	(6)		The Museum is illuminated by 250 burners, equal to 500 candles, about 3½ hours every night ☞ The whole expense of gas being about ⅞ of a dollar per night ☜

☞ As the above information is given with the knowledge & approbation of Mr Peale, it is perfectly at your service, to make what use of it you shall think proper.

Mr Peale gives credit to Dr Kugler for his present system of gas-lights; for which, I understand, he has obtained a patent.

If any further improvements, relative to this subject, should come to my knowledge, I shall take great pleasure in communicating them.