Improvements in and connected with the Preparation of Calcium Carbide for use in the Production of Acetylene Gas.
Year: 1897

page_text: Date of Application, 24th Nov., 1897
Complete Specification Left, 28th May, 1898-Accepted, 27th Aug., 1898
Improvements in and connected with the Preparation of Calcium
Carbide for use in the Production of Acetylene Gas.
I, WILLY JOSEF HUBERT LAZARUS, Doctor of Philosophy and Chemist, of 22,
Schenkelstrasse, Duren, in the Kingdom of Prussia, in the Empire of Germany,
do hereby declare the nature of this invention to be as follows:-
This invention relates to the production of acetylene-gas by the decomposition
of calcium carbide by means of water, and it has reference more especially to the
supply of water to the calcium-carbide, the object being to remove as far as possible
the inconveniences hitherto incidental to the production of acetylene-gas.
As hitherto practised the production of acetylene-gas from calcium carbide
by treating it with water presents the serious objections that, the evolution of
the gas takes place in a very violent and irregular manner, and the water and
also the decomposing apparatus are contaminated by the mud formed by the
calcium hydroxide which is the residue of the reaction between the carbide and
the water.
In attempting to prevent the mud of calcium hydroxide from diffusing into
the water and depositing on the walls of the vessel by employing large pieces of
carbide and enclosing them in a sufficiently resistant permeable cover or coating,
I have observed that when such enclosed pieces were immersed in water, the
evolution of gas did not cease after a short time, but continued very quietly and
uniformly until all of the calcium carbide was consumed. Moreover, there
occurred no objectionable contamination of the surrounding water though the
pieces were so placed that the gas escaping through the pores of the envelope or
coating passed through the water. When I removed an enveloped or coated
piece from the water previous to complete decomposition and re-placed it after
some time, the evolution of gas recommenced and continued as quietly and uni-
formly as before. By dividing such partially exhausted lumps into halves I
found a core of undecomposed calcium-carbide covered all around with a dense
layer of calcium hydroxide held against the said core by the envelope or coating,
the said layer being the thicker the longer the lump has been exposed to the
action of the water. This surrounding layer of calcium-hydroxide is in an almost
dry state next to the carbide core, whereas the remoter portions are the more
charged with moisture the nearer they are to the envelope or coating. This
curious phenomenon suggested the idea, which afterwards was proved true by
special experiments, that the calcium hydroxide is caused to perform the function
of a water feeder with regard to the adjoining calcium carbide in the following
manner. Owing to the extreme power with which calcium-carbide reacts with
water, the former at once absorbs all the water present in the adjoining portion
of the surrounding calcium-hydroxide; the thus completely dehydrated inner-

page_text: most portion of the latter takes water from the next portion and so on until the
envelope or coating is reached, the portion of the calcium hydroxide adjacent to
the said envelope or coating compensating for its loss of water from the surrounding
bulk of water, so that, the water is supplied to the carbide by the calcium-
hydroxide exerting a sucking action.
In view of this discovery this invention consists first in so carrying out the
production of acetylene gas by decomposing calcium carbide by means of water
that the latter is supplied to the carbide by the medium of the calcium hydroxide
left behind as the residue of the reaction, by maintaining the said residue in
close contact with the undecomposed portion of the carbide.
As the water supply is thus made dependent upon the water-loss occurring
in the portion, or portions, of the calcium hydroxide which is, or are, nearest
to the calcium carbide, the said supply is caused to take place continuously as
long as there is calcium carbide left to be acted upon by the water sucked in by
the calcium hydroxide, with the effect of giving continuity to the evolution of
the acetylene gas. As this evolution of gas is at any moment in proportion with the
water supply e. with the area of contact between the calcium carbide and
the adjoining calcium hydroxide, and as this area can easily be made uniform
in any section of the mass of calcium carbide by giving the latter a cylindrical
or prismatic shape, and the access of water to take place through one of the ends
of the latter, the evolution of the gas can be caused to take place in a quantita-
tively uniform manner.
In the second place my invention comprises a method of causing the calcium
hydroxide residue to form in the state of, or to be at once transformed into, a
self-coherent and self-adherent mass, so as to enable it to perform its function
as a water feeder to the calcium carbide without the assistance of a special
permeable retaining cover, envelope or coating.
Thirdly my invention provides as a new article of manufacture calcium-carbide
bodies enabling this invention to be employed with advantage for illuminating
purposes, the said bodies allowing the calcium carbide to be made an article
to he sold by retail.
I will now describe how the calcium-hydroxide obtained as a residue in the
manufacture of acetylene gas by treating calcium-carbide with water is made to
become active as a water-feeding medium.
Lumps or pieces of raw calcium carbide are ground to a very fine powder;
and this is made by pressure into a compact dense body of the desired shape and
size. In general it is preferred to give the body a cylindrical or prismatic form.
The body is enclosed in a well fitting permeable envelope open at one or both ends
and having sufficient strength to withstand the pressure of the gas and the
pressure due to the fact that the calcium hydroxide formed occupies a somewhat
larger volume than the earbide from which it originated. Such envelope may
for instance consist of a hollow cylinder or prism of porous earthenware, or of
wire-gauze of very fine mesh, and the like. The open end, or ends, of the said
envelope are closed with a suitable cover or covers. The operations of grinding,
compressing, and enveloping should be effected in as dry a room as possible in
order to exclude moisture. For enabling the body to be stored and conveyed
regardless of time and distance, the enveloped body, should be coated all around
with an impermeable substance such as paraffine, stearine, wax, mixtures, of
wax and turpentine, gelatine treated with bi-chromate of potassium or with
formaldehyde, after having been applied, and the like. Or the envelope is con-
structed of sheet metal, which I prefer in most cases, because it is practically
impermeable in itself, the open end being closed by a permeable cover and coated
as described.
Considering the difficulty of transforming finely powdered calcium carbişle
into a well self-coherent mass, I prefer to condense the powder into a sufficiently
strong envelope provided with a closed bottom, and an open end which is afterwards

page_text: closed as described, a sheet metal envelope being preferred as it is cheap and
permits a high pressure to be exerted upon the powder in condensing it.
When such an enveloped body of compressed or condensed calcium-carbide
powder with a portion from which the impermeable coating has been removed
is dipped into water, the water penetrates through such uncoated portion and
coming in contact with the calcium-carbide, at once decomposes the same at
the place of contact; the acetylene-gas generated escapes through the said un-
coated permeable portion whereas the residual calcium hydroxide is retained
between the envelope and the undecomposed calcium carbide, and as its volume
is greater than the volume of carbide from which it originates. it holds itself
in close contact with the carbide. The reaction going on continuously the calcium
hydroxide is caused to act as a water feeder in the manner described.
The aforesaid mode of preparing the calcium carbide for the utilisation of
the calcium hydroxide residue according to this invention, is somewhat imperfect
in that it requires a special permeable medium to be placed between the water
and the calcium hydroxide for retaining the latter in contact with the remaining
mass of calcium carbide. In order to obviate this objection and to cause the
calcium hydroxide particles to bind together into a self-coherent and self-adherent
mass I have invented the following method.
The raw calcium carbide lumps or pieces are impregnated with a liquid or
liquified cementing agent, which is indifferent towards both the water and the cal-
cium carbide and, moreover, is not liable to he ignited by the heat set free by the
reaction between the water and the calcium carbide. Suitable cementing agents
for the present purpose are paraffine stearine, wax, oils and the like. Of such
agent I prefer to apply up to 25 per cent. or thereabout. The impregnated lumps
or pieces are reduced to a fine powder, and this is compressed, or condensed, into
bodies of the desired shape and size preferably into bodies of cylindrical, or prism-
atic shape. When such a body is brought into contact with water, the latter
at once acts upon the outer particles of the calcium carbide which are decom-
posed into acetylene gas and calcium hydroxide. The heat generated by the
reaction is not sufficiently high for giving the cementing agent such fluidity as
would allow the same to fall apart taking with it the enclosed or adherent calcium
hydroxide particles, it being merely softened so as to form with the said particles
a permeable and adherent layer of a dough or paste-like nature.
This layer
grows thicker and thicker inwards as the decomposition of the calcium carbide
continues at its inner side. The place of heat generation thus progressing
inwards the remoter portions of the growing layer gradually cool and solidify.
The particles of this self-forming hydroxide layer are so well bound together
and to the adjacent calcium carbide, that portions thereof are not detached by
the combined action of the penetrating water, the escaping gas and gravity.
The same effect may be obtained by first grinding the carbide lumps or pieces:
mixing the powder with the cementing agent into a homogenous mass, dough
or paste, and compressing or condensing it.
This mode is however less advantageous as the grinding and mixing operations
require to be performed in places as free from moisture as possible.
I am aware that it has been proposed to impregnate small pieces of raw calcium
carbide with paraffine, oils and the like. and to immerse a quantity of such
pieces in water. It is evident that by these means the pieces cannot be prevented
from rapid dissolution into small particles under the combined action of the
penetrating water and the escaping gas, so that the hereinbefore mentioned incon-
veniences are not overcome.
I prefer to coat the body of cemented calcium carbide with an impermeable
substance such as paraffine, stearine, wax, wax mixed with turpentine, gelatine
rendered insoluble by treatment with formaldehyde, or bichromate, after having
been applied, and the like substances. It is preferred to employ for this purpose
an envelope of sheet metal of prismatic or cylindrical shape having an open end

page_text: for filling in and condensing the impregnated, powder obtained according to the
first mode, or the mixture as produced by employing the second mode the said
open end being finally closed by an impermeable layer, using for instance the
substances hereinbefore mentioned.
2
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,
Agents.
Improvements in and connected with the Preparation of Calcium
Carbide for use in the Production of Acetylene Gas.
I, WILLY JOSEF HUBERT LAZARUS, Doctor of Philosophy and Chemist, of 22,
Schenkelstrasse, Duren, in the Kingdom of Prussia, German Empire, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following state-
ment:-
This invention has reference to the production of acetylene gas by the action of
water upon calcium carbide which is presented to the water in the form of what
may be termed cartridges and the said invention relates to the manufacture of
such cartridges.
Calcium-carbide cartridges manufactured as usual are, in general, imperfect,
the evolution of gas taking place in a violent and irregular manner, so that
the water is contaminated by the mud formed, and the partially exhausted cart-
ridge, after removal from the water, does not allow of being exposed to the moist
atmosphere above the water without gas still being evolved therefrom.
.
The present invention obviates these inconveniences and consists in preparing
the calcium carbide cartridges so that the calcium carbide is acted upon by the
water in a very even or regular manner, by being presented to the water as a
regularly shaped compact body of even density, in which the carbide is present
in the form of very fine particles regularly distributed throughout its mass, the
calcium hydroxide resulting from the action of the water upon the carbide being
caused to form in the state of, or to be at once transformed into, a self-coherent
and self-adherent mass which is permeable to the water and the acetylene gas
generated, but the innermost layer of which, when the cartridge is removed from
the water, remains in intimate contact with the still undecomposed portion of the
cartridge, and constitutes a protecting coating for the said portion against the
access of the vapour-like moisture, or damp, contained in the atmosphere above
the water. This result. I obtain by the following improved process of manufactur-
ing the cartridges.
Lumps, or pieces. of raw calcium carbide are carefully impregnated with a
liquid, or liquified cementing agent, of a nature such that it is indifferent towards
both the water and the calcium carbide, and is not liable to be ignited, or distilled,
or otherwise acted upon, or rendered unefficacious, by the heat resulting from
the reaction between the water and the calcium carbide. Such cementing agents
are paraffine, paraffine-oils, stearine, wax and the like. Paraffine has proved
to give the best results. Of such agent up to 25 per cent. may be used, but I
prefer to employ from 3 to 5 per cent. Resins, varnishes, and the like, are not
suitable for the purposes of this invention as they undergo distillation, and con-

page_text: sequently the acetylene gas is infected by the products of such distillation; further
they combine with the calcium hydroxide formed, constituting a soap-like com-
pound which, though viscous to a certain degree, is continuously driven out
by the gas evolved, in innumerable bubbles across the water into the space
above, so that there is great liability to the exit for the gas being partly or
wholly obstructed; moreover the said bubbles carry with them numerous particles
of undecomposed carbide.
The lumps or pieces of calcium carbide, impregnated as aforesaid, are ground,
or otherwise reduced, to as fine a powder as possible, and this is compressed, by
means of a powerful press, into solid bodies of the desired shape and size, pre-
ferably into bodies of prismatic, or cylindrical, shape, which may finally be
coated with an impermeable substance such as paraffine, stearine, wax, wax mixed
with turpentine, gelatine (which is afterwards rendered insoluble by treatment with
formaldehyde or bichromate) and the like substances, I prefer to employ an
envelope of sheet metal, or other sufficiently resisting, and impervious material,
of prismatic, or cylindrical, shape, closed at one end and open at the other end,
through which the powder of impregnated carbide is forced into the envelope,
this mode of proceeding having the important advantage that no empty spaces are
left between the carbide and its envelope but an intimate contact is ensured.
The filling in end is after filling closed by a water and damp tight material, for
example a layer of paraffine, stearine, wax, or gelatine afterwards rendered insol-
uble by treatment with formaldehyde or bichromate.
When a cartridge of this description with the closing layer of paraffine or
the like wholly, or partly, removed, is placed in water the water at once acts
upon the exposed particles of the calcium carbide, decomposing it into acetylene
gas and calcium hydroxide. The heat generated by the reaction is not sufficiently
high to give the cementing agent mixed with the carbide such fluidity as will
allow it to drop taking with it the enclosed or adhering, particles of the calcium
hydroxide formed. The cementing agent is merely softened and thereby caused
to form, with the fine particles of calcium hydroxide generated, a dough- or
paste-like mass which is perfectly permeable to the water moistening it at the
outer side and to the gas evolving at its inner side, and which has such a coherence
in itself as not to be disintegrated, unless at the very beginning, by the action
of the penetrating water and the escaping gas, but forms a resisting layer in
the front of the undecomposed portion of the cartridge, the contact surfaces of
the said layer and portion adhering very strongly to each other. This layer
formed by the residue of the reaction, grows thicker and thicker inwards as
the decomposition of the calcium carbide continues at its inner side, and, as the
place of heat generation thus progresses inwards, the remoter, or outer, portions
of the growing layer gradually cool, whereby they assume a rather stiff condition.
The resisting layer of calcium hydroxide thus formed has the property that
its innermost portion, namely that portion which is in contact with and adheres
to, the unattacked portion of the carbide, is always in a practically dry state,
whereas the remoter portions are the more charged with moisture the nearer they
are to the water. When the evolution of gas is interrupted by removing the
cartridge from contact with the water, the innermost layer of cemented calcium-
hydrate particles remains strongly adherent to the undecomposed remainder of
calcium carbide, and constitutes a protecting cover for the carbide as it is perfectly
impervious to the moisture, or damp, contained in the surrounding atmosphere,
so that the evolution of acetylene gas ceases a very short time after removal of
the cartridge from the water. The cartridge can in this state be left in a very
wet atmosphere for an indefinite period without sensibly evolving acetylene gas,
but acetylene gas will at once recommence to evolve when the cartridge is replaced
in the water. It will be readily understood that this result, namely, the self
formation of a protective coating, or guard, against the access of vaporous moisture,
or damp, is an important improvement as it allows the cartridge to be repeatedly

page_text: used intermittently without decomposition of the calcium carbide at times when
gas is not needed.
This beneficial effect of my improved calcium carbide cartridge is due to the
fact that the calcium carbide is impregnated with the cementing agent, before
being reduced to powder, as by that means an extremely intimate intermixture
of the finest particles, such as is necessary to cause the residue to form a coherent
and adherent mass, is effected, and this cannot be obtained by first grinding
and then mixing as proposed heretofore.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that am aware
that it has before been proposed to grind the calcium carbide, to mix with paraf-
fine, resin, or other cementing agent, the carbide thus reduced, and to condense
the mixture in order to manufacture cartridges for the production of acetylene
gas, and therefore I do not broadly claim the use of paraffine, or resin, or their
equivalents in the manufacture of such cartridges, but what I claim is:-
-
1. The improvement in the manufacture of calcium carbide cartridges for the
production of acetylene gas, which improvement consists in first impregnating
the calcium carbide with paraffine, or other cementing agent, then reducing the
impregnated carbide to powder, and condensing the powder thus obtained into
a compact body, substantially as and for the purpose hereinbefore described.
2. The improvement in the manufacture of calcium carbide cartridges for the
production of acetylene gas, which improvement consists in first impregnating
the calcium carbide with paraffine or other cementing agent, then reducing the
impregnated carbide to powder, and forcing the powder into an envelope of sheet
metal, and closing the filling-in end of the said envelope by a substance imper-
meable to water and vapours, substantially as and for the purpose hereinbefore
described.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,
Agents.