CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR ILLUMINATION
Year: 1834

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JEAN
BAPTISTE MOLLERAT, now residing with Sir John Byerly, at Whitehead's
Grove, in the Parish of Saint Luke, Chelsea, in the County of Middlesex,
Manufacturing Chemist, send greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by Ilis Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Twenty-fifth day of September, in the fifth year of His
reign, did, for Himself, His heirs and successors, give and grant unto me, the
said Jean Baptiste Mollerat, His especial license, sole privilege and authority,
that I, the said Jean Baptiste Mollerat, my executors, administrators, and
assigns, and such others as I, the said Jean Baptiste Mollerat, my executors,
administrators, or assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF GAS FOR ILLUMINATION;"
in which said Letters Patent is contained a proviso that I, the said Jean
Baptiste Mollerat, shall cause a particular description of the nature of the said
Invention, and in what manner the same is to be performed, to be inrolled
in His said Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Jean Baptiste Molleratt, do hereby declare that the nature of the said

page_text: Invention, and in what manner the same is to be performed, is particularly
described and ascertained in and by the following description thereof (that is
to say)-
My Invention consists in utilizing the vapour of certain volatile liquids
which are very rich in carbon, to render luminous various gases which are not
so, though they are combustible. I employ for this purpose several volatile
liquids herein-after named.
First, the very volatile liquid obtained from the distillation of the tar
produced in the manufacture of gas or coke. The tar distilled at a gentle
heat furnishes an oil composed of the susquicarburet and the bicarburet of
hydrogen, containing generally in one hundred parts 91-2 of carbon and 8.8 of
hydrogen. It is known that the sesquicarburet of hydrogen contains 90-02
of carbon and 9.98 of hydrogen, and the bicarburet 92.35 of carbon and
7.65 of hydrogen. Each of these two bodies boil at 186° of Fahrenheit, and
possess a very great elasticity. Their density is the same, being 0.86, water
being 1 at the ordinary temperature. The liquid I employ will support a
degree of cold equal to the zero of Fahrenheit without solidifying, which
proves that it contains a sesquicarburet which remains liquid at that low
temperature, while the bicarburet becomes solid at the freezing point of
Fahrenheit. Coal tar produced in the manner above stated yields ten to
twelve per cent. of the volatile oil above mentioned, proper for the use of my
Patent, but the first product of this distillation is the only one proper to be
employed for that object, without being rectified. What comes over after-
wards is mixed with an oil that boils only at 212°, and contains, besides,
napthaline, which only boils at 380° of Fahrenheit. If this second product
were employed, a second distillation would be necessary, to get rid
of the oil and napthaline, in an apparatus on the principle of that of
Woolf. If coal were distilled for the express purpose of obtaining the
volatile oil, a greater per centage than the above would be produced.
Second, the natural products known under the names of naptha, petroleum
of Malta (mineral pitch), asphaltum, and bitumens, whether these matters are
found in a mixed state in sandstone, silieste, or limestone, or only in a liquid
state, or procured by the distillation of these mineral products. These matters
are all formed of carbon and hydrogen, but can only be employed after being
rectified so as to boil at about 212° of Fahrenheit.
Third, the oil obtained by the distillation of caoutchouc. The first oil that
comes over in this distillation at the ordinary temperature possesses a con-
siderable illuminating power. I also employ any other oils which are very
rich in carbon, and volatile enough to boil at 212° Fahrenheit. The gas

page_text: which render luminous by the addition of any of these oils is either pure
hydrogen, or a mixture of hydrogen, carbonated hydrogen, and carbonic
oxide. I obtain from hydrogen, by the processes described in all treatises of
chemistry, either by the decomposition of water by means of iron or zinc
and an acid, or by means of iron at an elevated temperature. The gas which
I prefer is that obtained in passing steam over red-hot charcoal reduced to a
state of dust or powder, or over red-hot coal. The gas is a mixture of hydrogen,
carbonic acid, carbonic oxide, and carburetted bydrogen, in variable quantities,
according to the mode of operation. When the apparatus is only gently
heated, there are produced hydrogen, much carbonic acid, and a small quantity
of carbonic oxide. When, on the contrary, the apparatus is properly heated,
and if the gas passes over a great excess of incandescent charcoal before it
arrives at the gasometer, it will produce hydrogen, much carbonic oxide, and
little or no carbonic acid. This gas may be produced in retorts similar to
those used for making coal gas, but I prefer an apparatus consisting of one or
more retorts, with a partition in the middle through the whole of the length.
These retorts, filled with charcoal, are placed horizontally in a furnace, and
so disposed that the steam of water passes through the whole length of the
under half of the retort, and return through the whole length of the upper
half into a pipe leading to the gasometer. This mode is adopted in order
that the water may be forced to pass through a great excess of red-hot
charcoal, and thus produce the least possible of carbonic acid, and the greatest
quantity of carbonic oxide. Instead of the partition above named, retorts may
be connected together with pipes, so as to obtain the same effect. The retorts
may also be placed vertically. In this case receivers or vases, holding
charcoal, should be adapted to the other end, closing hermetically, and thus
furnish a supply of charcoal to the retort as it is wanted. When the gas is
thus prepared, there is no occasion to wash it, as it will be then almost entirely
composed of hydrogen and carbonic oxide, in nearly equal portions, and a
certain quantity of carbonated hydrogen. To render the gas luminous, a
current from the gasometer is passed in a vessel containing one of the volatile
oils mentioned above. A part of the oil is converted into vapour and
carried off by the gas, and even before the gas has taken up enough to
be saturated it has acquired a luminous quality sufficient for the purpose of
lighting. When the temperature of the atmosphere is below 60, the vessel
containing the oil must be warmed until it has attained that temperature,
which may be done by a small pipe from the gasometer placed under it,
and firing the gas, or by keeping the vessel in warm water, maintaining
it at the temperature of 60° at least. The vessel containing the oil ought

page_text: to be so arranged that the gas which arrives may always take up the.
same quantity of volatile oil which then passes into the service pipes for use.
The volatile oil may be mixed with the gas on its passage from the retorts
to the gasometer or in the gasometer itself, but I prefer the first method
as the most advantageous. One pound of charcoal will produce at least fifty
cubic feet of gas, and each cubic foot of gas requires from 40 to 50 grains
of the oil distilled from coal tar. Two pounds of water furnishes by its
Invention
decomposition about eight hundred gallons of gas. I claim as my
the method of decomposing water by charcoal, so as to be free from carbonic
acid without washing, which previously was always indispensable. I claim
also the having ascertained by direct experiment the chemical and physical
qualities of the volatile oils necessary for rendering water gas luminous and
support the changes of temperature, inasmuch as they must be in the state of a
sesquicarburet and boilt at a temperature inferior to that of water. I also
claim as new, the having determined the quantity of volatile oil necessary
to be combined with a given quantity of water gas, to render it highly
luminous. I likewise claim as my Invention the method of combining the
volatile oils and the water gas, as well as the temperature at which those oils
should be maintained in order to their being taken up in a sufficient quantity
by the gas before it passes into the service pipes.
In witness whereof, I, the said Jean Baptiste Mollerat, have hereunto
set my hand and seal, this Eighteenth day of March, in the year
of our Lord One thousand eight hundred and thirty-five.