Joseph Coppinger - "The American Practical Brewer and Tanner"

Richard F. Burton - "The Book of the Thousand Nights and a Night, Volume 1"

Jean de La Fontaine - "The Fables of La Fontaine"

James Hay, Jr. - "The Winning Clue"

Annual Bibliography of Commonwealth Literature 2007
This paper argues that discourses of love in Ghanaian market literature for youth offer a view into complex negotiations of agency and empowerment. Drawing on Deborah Durham's notion of youth as "social `shifters'" and Francis Nyamnjoh's conception of the "interconnectedness" of agency, I take Ghanaian market literature as one specific case of how African literature for youth foregrounds questions of continuity and change as African societies enter into increasingly complex global relations. In this literature for youth, received notions of love, often constructed out of impressions from American pop and hip hop music, carry new notions of agency that compete with existing "domesticated" forms. Authors like Ike Tandoh and Evelyn Tay employ discourses of love to offer youth alternative avenues for empowerment in a context of socio-economic disenfranchizement. In a creative process of "straddling", this writing both reveals and reproduces the contradictions that obtain in youth configurations of agency.

Acetylene, The Principles Of Its Generation And Use

F >> F. H. Leeds and W. J. Atkinson Butterfield >> Acetylene, The Principles Of Its Generation And Use




AUTOMATIC AND NON-AUTOMATIC GENERATORS.--Before proceeding to a detailed
description of the various devices which may be adopted to render an
acetylene generator automatic in action, the relative advantages of
automatic and non-automatic apparatus, irrespective of type, from the
consumer's point of view may be discussed. The fundamental idea
underlying the employment of a non-automatic generator is that the whole
of the calcium carbide put into the apparatus shall be decomposed into
acetylene as soon after the charge is inserted as is natural in the
circumstances; so that after a very brief interval of time the generating
chambers shall contain nothing but spent lime and water, and the holder
be as full of gas as is ever desirable. In an automatic apparatus, the
fundamental idea is that the generating chamber, or one at least of
several generating chambers, shall always contain a considerable quantity
of undecomposed carbide, and some receptacle always contain a store of
water ready to attack that carbide, so that whenever a demand for gas
shall arise everything may be ready to meet it. Inasmuch as acetylene is
an inflammable gas, it possesses all the properties characteristic of
inflammable gases in general; one of which is that it is always liable to
take fire in presence of a spark or naked light, and another of which is
that it is always liable to become highly explosive in presence of a
naked light or spark if, accidentally or otherwise, it becomes mixed with
more than a certain proportion of air. On the contrary, in the complete
absence of liquid or vaporised water, calcium carbide is almost as inert
a body as it is possible to imagine: for it will not take fire, and
cannot in any circumstances be made to explode. Hence it may be urged
that a non-automatic generator, with its holder always containing a large
volume of the actually inflammable and potentially explosive acetylene,
must invariably be more dangerous than an automatic apparatus which has
less or practically no ready-made gas in it, and which simply contains
water in one chamber and unaltered calcium carbide in another. But when
the generating vessels and the holder of a non-automatic apparatus are
properly designed and constructed, the gas in the latter is acetylene
practically free from air, and therefore while being, as acetylene
inevitably is, inflammable, is devoid of explosive properties, always
assuming, as must be the case in a water-sealed holder, that the
temperature of the gas is below 780 deg. C.; and also assuming, as must
always be the case in good plant, that the pressure under which the gas
is stored remains less than two atmospheres absolute. It is perfectly
true that calcium carbide is non-inflammable and non-explosive, that it
is absolutely inert and incapable of change; but so comprehensive an
assertion only applies to carbide in its original drum, or in some
impervious vessel to which moisture and water have no access. Until it is
exhausted, an automatic acetylene generator contains carbide in one place
and water in another, dependence being put upon some mechanical
arrangement to prevent the two substances coming into contact
prematurely. Many of the devices adopted by builders of acetylene
apparatus for keeping the carbide and water separate, and for mixing them
in the requisite quantities when the proper time arrives, are as
trustworthy, perhaps, as it is possible for any automatic gear to be; but
some are objectionably complicated, and a few are positively inefficient.
There are two difficulties which the designer of automatic mechanism has
to contend with, and it is doubtful whether he always makes a sufficient
allowance for them. The first is that not only must calcium carbide and
liquid water be kept out of premature contact, but that moisture, or
vapour of water, must not be allowed to reach the carbide; or
alternatively, that if water vapour reaches the carbide too soon, the
undesired reaction shall not determine overheating, and the liberated gas
be not wasted or permitted to become a source of danger. The second
difficulty encountered by the designer of automata is so to construct his
apparatus that it shall behave well when attended to by completely
unskilled labour, that it shall withstand gross neglect and resist
positive ill-treatment or mismanagement. If the automatic principle is
adopted in any part of an acetylene apparatus it must be adopted
throughout, so that as far as possible--and with due knowledge and skill
it is completely possible--nothing shall be left dependent upon the
memory and common sense of the gasmaker. For instance, it must not be
necessary to shut a certain tap, or to manipulate several cocks before
opening the carbide vessel to recharge it; it must not be possible for
gas to escape backwards out of the holder; and either the carbide-feed
gear or the water-supply mechanism (as the case may be) must be
automatically locked by the mere act of taking the cover off the carbide
store, or of opening the sludge-cock at the bottom. It would be an
advantage, even, if the purifiers and other subsidiary items of the plant
were treated similarly, arranging them in such fashion that gas should be
automatically prevented from escaping out of the rest of the apparatus
when any lid was removed. In fact, the general notion of interlocking,
which has proved so successful in railway signal-cabins and in
carburetted water gas-plant for the prevention of accidents duo to
carelessness or overnight, might be copied in principle throughout an
acetylene installation whenever the automatic system is employed.

It is no part of the present argument, to allege that automatic
generators are, and must always be, inherently dangerous. Automatic
devices of a suitable kind may be found in plenty which are remarkably
simple and highly trustworthy; but it would be too bold a statement to
say that any such arrangement is incapable of failure, especially when
put into the hands of a person untrained in the superintendence of
machinery. The more reliable a piece of automatic mechanism proves itself
to be, the more likely is it to give trouble and inconvenience and
utterly to destroy confidence when it does break down; because the better
it has behaved in the past, and the longer it has lasted without
requiring adjustment, the less likely is it that the attendant will be at
hand when failure occurs. By suitable design and by an intelligent
employment of safety-valves and blow-off pipes (which will be discussed
in their proper place) it is quite easy to avoid the faintest possibility
of danger arising from an increase of pressure or an improper
accumulation of gas inside the plant or inside the building containing
the plant; but every time such a safety-valve or blow-off pipe comes into
action a waste of gas occurs, which means a sacrifice of economy, and
shows that the generator is not working as it should.

As glass is a fragile and brittle substance, and as it is not capable of
bearing large, rapid, and oft-repeated alterations of temperature in
perfect safety, it is not a suitable material for the construction of
acetylene apparatus or of portions thereof. Hence it follows that a
generator must be built of some non-transparent material which prevents
the interior being visible when the apparatus is at work. Although it is
comparatively easy, by the aid of a lamp placed outside the generator-
shed in such a position as to throw its beams of light through a window
upon the plant inside, to charge a generator after dark; and although it
is possible, without such assistance, by methodical habits and a
systematic arrangement of utensils inside the building to charge a
generator even in perfect darkness, such an operation is to be
deprecated, for it is apt to lead to mistakes, it prevents any slight
derangement in the installation from being instantly noticed, and it
offers a temptation to the attendant to break rules and to take a naked
light with him. On all those grounds, therefore, it is highly desirable
that every manipulation connected with a generator shall be effected
during the daytime, and that the apparatus-house shall be locked up
before nightfall. But owing to the irregular habits engendered by modern
life it is often difficult to know, during any given day, how much gas
will be required in the ensuing evening; and it therefore becomes
necessary always to have, as ready-made acetylene, or as carbide in a
proper position for instant decomposition, a patent or latent store of
gas more than sufficient in quantity to meet all possible requirements.
Now, as already stated, a non-automatic apparatus has its store of
material in the form of gas in a holder; and since this is preferably
constructed on the rising or telescopic principle, a mere inspection of
the height of the bell--on which, if preferred, a scale indicating its
contents in cubic feet or in burner-hours may be marked--suffices to show
how near the plant is to the point of exhaustion. In many types of
automatic apparatus the amount of carbide remaining undecomposed at any
moment is quite unknown, or at best can only be deduced by a tedious and
inexact calculation; although in some generators, where the store of
carbide is subdivided into small quantities, or placed in several
different receptacles, an inspection of certain levers or indicators
gives an approximate idea as to the capacity of the apparatus for further
gas production. In any case the position of a rising holder is the most
obvious sign of the degree of exhaustion of a generator; and therefore,
to render absolutely impossible a failure of the light during an evening,
a non-automatic generator fitted with a rising holder is best.

Since calcium carbide is a solid body having a specific gravity of 2.2,
water being unity, and since 1 cubic foot of water weighs 62.4 lb., in
round numbers 137 lb. of _compact_ carbide only occupy 1 cubic foot
of space. Again, since acetylene is a gas having a specific gravity of
0.91, air being unity, and since the specific gravity of air, water being
unity, is 0.0013, the specific gravity of acetylene, water being unity,
is roughly O.00116. Hence 1 cubic foot of acetylene weighs roughly 0.07
lb. Furthermore, since 1 lb. of good carbide evolves 5 cubic feet of gas
on decomposition with water, acetylene stored at atmospheric pressure
occupies roundly 680 times as much space as the carbide from which it has
been evolved. This figure by no means represents the actual state of
affairs in a generator, because, as was explained in the previous
chapter, a carbide vessel cannot be filled completely with solid; and,
indeed, were it so "filled," in ordinary language, much of its space
would be still occupied with air. Nevertheless it is incontrovertible
that an acetylene plant calculated to supply so many burners for so long
a period of time must be very much larger if it is constructed on the
non-automatic principle, when the carbide is decomposed all at once, than
if the automatic system is adopted, when the solid remains unattacked
until a corresponding quantity of gas is required for combustion. Clearly
it is the storage part of a non-automatic plant alone which must be so
much larger; the actual decomposing chambers may be of the same size or
even smaller, according to the system of generation to which the
apparatus belongs. In practice this extra size of the non-automatic plant
causes it to exhibit two disadvantages in comparison with automatic
apparatus, disadvantages which are less serious than they appear, or than
they may easily be represented to be. In the first place, the non-
automatic generator requires more space for its erection. If acetylene
were an illuminating agent suitable for adoption by dwellers in city or
suburb, where the back premises and open-air part of the messuage are
reduced to minute proportions or are even non-existent, this objection
might well be fatal. But acetylene is for the inhabitant of a country
village or the occupier of an isolated country house; and he has usually
plenty of space behind his residence which he can readily spare. In the
second place, the extra size of the non-automatic apparatus makes it more
expensive to construct and more costly to instal. It is more cosily to
construct and purchase because of its holder, which must be well built on
a firm foundation and accurately balanced; it is more costly to instal
because a situation must be found for the erection of the holder, and the
apparatus-house may have to be made large enough to contain the holder as
well as the generator itself. As regards the last point, it may be said
at once that there is no necessity to place the holder under cover: it
may stand out of doors, as coal-gas holders do in England, for the seal
of the tank can easily be rendered frost-proof, and the gas itself is not
affected by changes of atmospheric temperature beyond altering somewhat
in volume. In respect of the other objections, it must be remembered that
the extra expense is one of capital outlay alone, and therefore only
increases the cost of the light by an inappreciable amount, representing
interest and depreciation charges on the additional capital expenditure.
The increased cost of a year's lighting due to these charges will amount
to only 10 or 15 per cent, on the additional capital sunk. The extra
capital sunk does not in any way increase the maintenance charges; and
if, by having a large holder, additional security and trustworthiness are
obtained, or if the holder leads to a definite, albeit illusive, sense of
extra security and trustworthiness, the additional expenditure may well
be permissible or even advantageous.

The argument is sometimes advanced that inasmuch as for the same, or a
smaller, capital outlay as is required to instal a non-automatic
apparatus large enough to supply at one charging the maximum amount of
light and heat that can ever be needed on the longest winter's night, an
automatic plant adequate to make gas for two or three evenings can be
laid down, the latter must be preferable, because the attendant, in the
latter case, will only need to enter the generator-house two or three
times a week. Such an argument is defective because it ignores the
influence of habit upon the human being. A watch which must be wound
every day, or a clock which must be wound every week, on a certain day of
the week, is seldom permitted to run down; but a watch requiring to be
re-wound every other day, or a fourteen-day clock (used as such), would
rarely be kept going. Similarly, an acetylene generator might be charged
once a week or once a day without likelihood of being forgotten; but the
operation of charging at irregular intervals would certainly prove a
nuisance. With a non-automatic apparatus containing all its gas in the
holder, the attendant would note the position of the bell each morning,
and would introduce sufficient carbide to fill the holder full, or partly
full, as the case might be; with an automatic apparatus he would be
tempted to trust that the carbide holders still contained sufficient
material to last another night.

The automatic system of generating acetylene has undoubtedly one
advantage in those climates where frost tends to occur frequently, but
only to prevail for a short period. As the apparatus is in operation
during the evening hours, the heat evolved will, or can be made to,
suffice to protect the apparatus from freezing until the danger has
passed; whereas if the gas is generated of a morning in a non-automatic
apparatus the temperature of the plant may fall to that of the atmosphere
before evening, and some portion may freeze unless special precautions
are taken to protect it.

It was shown in Chapter II that overheating is one of the chief troubles
to be guarded against in acetylene generators, and that the temperature
attained is a function of the speed at which generation proceeds. Seeing
that in an automatic apparatus the rate of decomposition depends on the
rate at which gas is being burnt, while in a non-automatic generator it
is, or may be, under no control, the critic may urge that the reaction
must take place more slowly and regularly, and the maximum temperature
therefore be lower, when the plant works automatically. This may be true
if the non-automatic generator is unskilfully designed or improperly
manipulated; but it is quite feasible to arrange an apparatus, especially
one of the carbide-to-water or of the flooded-compartment type, in such
fashion that overheating to an objectionable extent is rendered wholly
impossible. In a non-automatic apparatus the holder is nothing but a
holder and may be placed wherever convenient, even at a distance from the
generating plant; in an automatic apparatus the holder, or a small
similarly constructed holder placed before the main storage vessel, has
to act as a water-supply governor, as the releasing gear for certain
carbide-food mechanism, or indeed as the motive power of such mechanism;
and accordingly it must be close to the water or carbide store, and more
or less intimately connected by means of levers, or the like, with the
receptacle in which decomposition occurs. Sometimes the holder surrounds,
or is otherwise an integral part of, the decomposing chamber, the whole
apparatus being made self-contained or a single structure with the object
of gaining compactness. But it is evident that such methods of
construction render additionally awkward, or even hazardous, any repair
or petty operation to the generating portion of the plant; while the more
completely the holder is isolated from the decomposing vessels the more
easily can they be cleaned, recharged, or mended, without blowing off the
stored gas and without interfering with the action of any burners that
may be alight at the time. Owing to the ingenuity of inventors, and the
experience they have acquired in the construction of automatic acetylene
apparatus during the years that the gas has been in actual employment, it
is going too far boldly to assert that non-automatic generators are
invariably to be preferred before their rivals. Still in view of the
nature of the labour which is likely to be bestowed on any domestic
plant, of the difficulty in having repairs or adjustments done quickly in
outlying country districts, and of the inconvenience, if not risk,
attending upon any failure of the apparatus, the greater capital outlay,
and the larger space required by non-automatic generators are in most
instances less important than the economy in space and prime cost
characteristic of automatic machines when the defects of each are weighed
fairly in the balance. Indeed, prolonged experience tends to show that a
selection between non-automatic and automatic apparatus may frequently be
made on the basis of capacity. A small plant is undoubtedly much more
convenient if automatic; a very large plant, such as that intended for a
public supply, is certainly better if non-automatic, but between these
two extremes choice may be exercised according to local conditions.

CONTROL OF THE CHEMICAL REACTION.--Coming now to study the principles
underlying the construction of an acetylene generator more closely it
will be seen that as acetylene is produced by bringing calcium carbide
into contact with water, the chemical reaction may be started either by
adding the carbide to the water, or by adding the water to the carbide.
Similarly, at least from the theoretical aspect, the reaction, may be
caused to stop by ceasing to add carbide to water, or by ceasing to add
water to carbide. Apparently if water is added by degrees to carbide,
until the carbide is exhausted, the carbide must always be in excess; and
manifestly, if carbide is added in small portions to water, the water
must always be in excess, which, as was argued in Chapter II., is
emphatically the more desirable position of affairs. But it in quite
simple to have carbide present in large excess of the water introduced
when the whole generator is contemplated, and yet to have the water
always in chemical excess in the desired manner; because to realise the
advantages of having water in excess, it is only necessary to subdivide
the total charge of carbide into a number of separate charges which are
each so small that more than sufficient water to decompose and flood one
of them is permitted to enter every time the feed mechanism comes into
play, or (in a non-automatic apparatus) every time the water-cock is
opened; so arranging the charges that each one is protected from the
water till its predecessor, or its predecessor, have been wholly
decomposed. Thus it is possible to regard either the carbide or the water
as the substance which has to be brought into contact with the other in
specified quantity. It is perhaps permissible to repeat that in the
construction of an automatic generator there is no advantage to be gained
from regulating the supply of both carbide and water, because just as the
mutual decomposition will begin immediately any quantity of the one meets
any quantity of the other, so the reaction will cease (except in one case
owing to "after-generation") directly the whole of that material which is
not in chemical excess has been consumed-quite independently of the
amount of the other material left unattacked. Being a liquid, and
possessing as such no definite shape or form of its own irrespective of
the vessel in which it is held, water is by far the more convenient of
the two substances to move about or to deliver in predetermined volume to
the decomposing chamber. A supply of water can be started instantaneously
or cut oil as promptly by the movement of a cock or valve of the usual
description; or it may be allowed to run down a depending pipe in
obedience to the law of gravitation, and stopped from running down such a
pipe by opposing to its passage a gas pressure superior to that
gravitational force. In any one of several obvious ways the supply of
water to a mass of carbide may be controlled with absolute certainty, and
therefore it should apparently follow that the make of acetylene should
be under perfect control by controlling the water current. On the other
hand, unless made up into balls or cartridges of some symmetrical form,
calcium carbide exists in angular masses of highly irregular shape and
size. Its lumps alter in shape and size directly liquid water or moisture
reaches them; a loose more or loss gritty powder, or a damp cohesive mud,
being produced which is well calculated to choke any narrow aperture or
to jam any moving valve. It is more difficult, therefore, by mechanical
agency to add a supply of carbide to a mass of water than to introduce a
supply of water to a stationary mass of carbide; and far more difficult
still to bring the supply of carbide under perfect control with the
certainty that the movement shall begin and stop immediately the proper
time arrives.

But assuming the mechanical difficulties to be satisfactorily overcome,
the plan of adding carbide to a stationary mass of water has several
chemical advantages, first, because, however the generator be
constructed, water will be in excess throughout the whole time of gas
production; and secondly, because the evolution of acetylene will
actually cease completely at the moment when the supply of carbide is
interrupted. There is, however, one particular type of generator in which
as a matter of fact the carbide is the moving constituent, viz., the
"dipping" apparatus (cf. _infra_), to which these remarks do not
apply; but this machine, as will be seen directly, is, illogically
perhaps, but for certain good reasons, classed among the water-to-carbide
apparatus. All the mechanical advantages are in favour, as just
indicated, of making water the moving substance; and accordingly, when
classified in the present manner, a great majority of the generators now
on the markets are termed water-to-carbide apparatus. Their disadvantages
are twofold, though these may be avoided or circumvented: in all types
save one the carbide is in excess at the immediate place and time of
decomposition; and in all types without exception the carbide in the
whole of the generator is in excess, so that the phenomenon of "after-
generation" occurs with more or less severity. As explained in the last
chapter, after-generation is the secondary production of acetylene which
takes place more or less slowly after the primary reaction is finished,
proceeding either between calcium hydroxide, merely damp lime, or damp
gas and calcium carbide, with an evolution of more acetylene. As it is
possible, and indeed usual, to fit a holder of some capacity even to an
automatic generator, the simple fact that more acetylene is liberated
after the main reaction is over does not matter, for the gas can be
safely stored without waste and entirely without trouble or danger. The
real objection to after-generation is the difficulty of controlling the
temperature and of dissipating the heat with which the reaction is
accompanied. It will be evident that the balance of advantage, weighing
mechanical simplicity against chemical superiority, is somewhat even
between carbide-to-water and water-to-carbide generators of the proper
type; but the balance inclines towards the former distinctly in the ease
of non-automatic apparatus, and points rather to the latter when
automatism is desired. In the early days of the industry it would have
been impossible to speak so favourably of automatic carbide-to-water
generators, for they were at first constructed with absurdly complicated
and unreliable mechanism; but now various carbide-feed gears have been
devised which seem to be trustworthy even when carbide not in cartridge
form is employed.

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