Abraham Tomlinson - "The Military Journals of Two Private Soldiers, 1758 1775"

Arthur J. Rees - "The Hand in the Dark"

Selected by Beverly Nichols - "Book of Old Ballads"

Maria J. McIntosh - "Evenings at Donaldson Manor"

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




TABLE (B).

Giving the Sizes of Pipe which should be used in practice for Acetylene
when the fall of pressure in the Pipe is not to exceed 0.1 inch. (Based
on Morel's formula.)

________________________________________________________
| | |
| Cubic Feet of | Diameters of Pipe to be used up to |
| Acetylene | the lengths indicated. |
| which the Pipe |_______________________________________|
| is required to | | | | | |
| pass in | 1/4 | 3/8 | 1/2 | 3/4 | 1 |
| One Hour. | inch. | inch. | inch. | inch. | inch. |
|________________|_______|_______|_______|_______|_______|
| | | | | | |
| | Feet. | Feet. | Feet. | Feet. | Feet. |
| 1 | 520 | 3960 | 16700 | ... | ... |
| 2 | 130 | 990 | 4170 | ... | ... |
| 3 | 58 | 440 | 1850 | ... | ... |
| 4 | 32 | 240 | 1040 | ... | ... |
| 5 | 21 | 150 | 660 | 5070 | ... |
| 6 | 14 | 110 | 460 | 3520 | ... |
| 7 | 10 | 80 | 340 | 2590 | ... |
| 8 | ... | 62 | 260 | 1980 | ... |
| 9 | ... | 49 | 200 | 1560 | ... |
| 10 | ... | 39 | 160 | 1270 | 5340 |
| 15 | ... | 17 | 74 | 560 | 2370 |
| 20 | ... | 10 | 41 | 310 | 1330 |
| 25 | ... | ... | 26 | 200 | 850 |
| 30 | ... | ... | 18 | 140 | 590 |
| 35 | ... | ... | 13 | 100 | 430 |
| 40 | ... | ... | 10 | 79 | 330 |
| 45 | ... | ... | ... | 62 | 260 |
| 50 | ... | ... | ... | 50 | 210 |
|________________|_______|_______|_______|_______|_______|

TABLE (A).

Showing the Quantities [Q] (in cubic feet) of Acetylene which will pass
in One Hour through Pipes of various diameters (in inches) under
different Falls of Pressure. (Based on Morel's formula.)

____________________________________________________________________
| | | | | | | | | | | | |
| Diameter | | | | | | | | | | | |
| of Pipe | 1/4| 3/8| 1/2| 3/4 | 1 | 1 | 1 | 1 | 2 | 2 | 3 |
| [_d_] = | | | | | | 1/4 | 1/2| 3/4| | 1/2| |
| inches | | | | | | | | | | | |
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 0.10 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 10 | 7.2|19.9|40.8|112 |230 |405 | 635| 935|1305|2285|3600|
| 25 | 4.5|12.6|25.8| 71.2|146 |255 | 400| 590| 825|1445|2280|
| 50 | 3.2| 8.9|18.3| 50.3|103 |180 | 285| 420| 585|1020|1610|
| 100 | 2.3| 6.3|12.9| 35.6| 73.1|127 | 200| 295| 410| 720|1140|
| 200 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
| 300 | 1.3| 3.6| 7.4| 20.5| 42.2| 73.7| 116| 171| 240| 415| 655|
| 400 | 1.1| 3.1| 6.4| 17.8| 36.5| 63.8| 100| 148| 205| 360| 570|
| 500 | 1.0| 2.8| 5.8| 15.9| 32.7| 57.1| 90| 132| 185| 320| 510|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 0.25 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 25 | 7.2|19.9|40.8|112 |230 |405 | 635| 935|1305|2285|3600|
| 50 | 5.1|14.1|28.9| 79.6|163 |285 | 450| 660| 925|1615|2550|
| 100 | 3.6| 9.9|20.4| 56.3|115 |200 | 320| 470| 655|1140|1800|
| 250 | 2.3| 6.3|12.9| 35.6| 73.1|127 | 200| 295| 410| 720|1140|
| 500 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
| 1000 | 1.1| 3.1| 6.4| 17.8| 36.5| 63.8| 100| 148| 205| 360| 570|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 0.50 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 25 |10.2|28.1|57.8|159 |325 |570 | 900|1325|1850|3230|5095|
| 50 | 7.2|19.9|40.8|112 |230 |405 | 635| 935|1305|2285|3600|
| 100 | 5.1|14.1|28.9| 79.6|163 |285 | 450| 660| 925|1615|2550|
| 250 | 3.2| 8.9|18.3| 50.3|103 |180 | 285| 420| 585|1020|1610|
| 500 | 2.3| 6.3|12.9| 35.6| 73.1|127 | 200| 295| 410| 720|1140|
| 1000 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 0.75 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 50 | 8.8|24.4|50.0|138 |280 |495 | 780|1145|1160|2800|4410|
| 100 | 6.2|17.2|35.4| 97.5|200 |350 | 550| 810|1130|1980|3120|
| 250 | 3.9|10.9|22.4| 61.7|126 |220 | 350| 510| 715|1250|1975|
| 500 | 2.8| 7.7|15.8| 43.6| 89.5|156 | 245| 360| 505| 885|1395|
| 1000 | 2.0| 5.4|11.2| 30.8| 63.3|110 | 174| 255| 360| 625| 985|
| 2000 | 1.4| 3.8| 7.9| 21.8| 44.8| 78.2| 123| 181| 250| 440| 695|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 1.0 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 100 | 7.2|19.9|40.8|112 |230 |405 | 635| 935|1305|2285|3600|
| 250 | 4.5|12.6|25.8| 71.2|146 |255 | 400| 590| 825|1445|2280|
| 500 | 3.2| 8.9|18.3| 50.3|103 |180 | 285| 420| 585|1020|1610|
| 1000 | 2.3| 6.3|12.9| 35.6| 73.1|127 | 200| 295| 410| 720|1140|
| 2000 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
| 3000 | 1.3| 3.6| 7.4| 20.5| 42.2| 73.7| 116| 171| 240| 415| 655|
|__________|_________________________________________________________|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 1.5 inch. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 250 | 5.6|15.4|31.6| 87.2|179 |310 | 495| 725|1010|1770|2790|
| 500 | 3.9|10.9|22.4| 61.7|126 |220 | 350| 510| 715|1250|1975|
| 1000 | 2.8| 7.7|15.8| 43.6| 89.5|156 | 245| 360| 505| 885|1395|
| 2000 | 2.0| 5.4|11.2| 30.8| 63.3|110 | 174| 255| 360| 625| 985|
| 3000 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
| 4000 | 1.4| 3.8| 7.9| 21.8| 44.8| 78.2| 123| 181| 250| 440| 695|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|
| | |
| Length | |
| of Pipe | |
| [_l_] = | Fall of Pressure in the Pipe [_h_] = 2.0 inches. |
| Feet | |
|__________|_________________________________________________________|
| | | | | | | | | | | | |
| 500 | 4.5|12.6|25.8| 71.2|146 |255 | 400| 590| 825|1445|2280|
| 1000 | 3.2| 8.9|18.3| 50.3|103 |180 | 285| 420| 585|1020|1610|
| 2000 | 2.3| 6.3|12.9| 35.6| 73.1|127 | 200| 295| 410| 720|1140|
| 3000 | 1.8| 5.1|10.5| 29.1| 59.7|104 | 164| 240| 335| 590| 930|
| 4000 | 1.6| 4.4| 9.1| 25.2| 51.7| 90.3| 142| 210| 290| 510| 805|
| 5000 | 1.4| 4.0| 8.1| 22.5| 46.2| 80.8| 127| 187| 260| 455| 720|
| 6000 | 1.3| 3.6| 7.4| 20.5| 42.2| 73.7| 116| 171| 240| 415| 655|
|__________|____|____|____|_____|_____|_____|____|____|____|____|____|

NOTE.--In order not to impart to the above table the appearance of the
quantities having been calculated to a degree of accuracy which has no
practical significance, quantities of less than 5 cubic feet have been
ignored when the total quantity exceeds 200 cubic feet, and fractions of
a cubic foot have been included only when the total quantity is less than
100 cubic feet.

TABLE (C).

Giving the Sizes of Pipe which should be used in practice for Acetylene
when the fall of pressure in the Pipe is not to exceed 0.25 inch. (Based
on Morel's formula.)

____________________________________________________________________
| | |
| Cubic feet | |
| of | |
| Acetylene | Diameters of Pipe to be used up to the lengths stated.|
| which the | |
| Pipe is | |
| required |_______________________________________________________|
| to pass | | | | | | | | |
| in One | 1/4 | 1/2 | 3/4 | 1 | 1-1/4| 1-1/2| 1-3/4| 2 |
| Hour | inch.| inch.| inch.| inch.| inch.| inch.| inch.| inch.|
|____________|______|______|______|______|______|______|______|______|
| | | | | | | | | |
| | Feet.| Feet.| Feet.| Feet.| Feet.| Feet.| Feet.| Feet.|
| 2-1/2 | 1580 | 6680 | 50750| ... | ... | ... | ... | ... |
| 5 | 390 | 1670 | 12690| 53160| ... | ... | ... | ... |
| 7-1/2 | 175 | 710 | 5610| 23760| ... | ... | ... | ... |
| 10 | 99 | 410 | 3170| 13360| 40790| ... | ... | ... |
| 15 | 41 | 185 | 1410| 5940| 18130| 45110| ... | ... |
| 20 | 24 | 105 | 790| 3350| 10190| 25370| 54840| ... |
| 25 | 26 | 67 | 500| 2130| 6520| 16240| 35100| ... |
| 30 | 11 | 46 | 350| 1480| 4530| 11270| 24370| 47520|
| 35 | ... | 34 | 260| 1090| 3330| 8280| 17900| 34910|
| 40 | ... | 26 | 195| 830| 2550| 6340| 13710| 26730|
| 45 | ... | 20 | 155| 660| 2010| 5010| 10830| 21120|
| 50 | ... | 16 | 125| 530| 1630| 4060| 8770| 17110|
| 60 | ... | 11 | 88| 370| 1130| 2880| 6090| 11880|
| 70 | ... | ... | 61| 270| 830| 2070| 4470| 8730|
| 80 | ... | ... | 49| 210| 630| 1580| 3420| 6680|
| 90 | ... | ... | 39| 165| 500| 1250| 2700| 5280|
| 100 | ... | ... | 31| 130| 400| 1010| 2190| 4270|
| 150 | ... | ... | 14| 59| 180| 450| 970| 1900|
| 200 | ... | ... | ... | 33| 100| 250| 540| 1070|
| 250 | ... | ... | ... | 21| 65| 160| 350| 680|
| 500 | ... | ... | ... | ... | 16| 40| 87| 170|
| 1000 | ... | ... | ... | ... | ... | 10| 22| 42|
|____________|______|______|______|______|______|______|______|______|

TABLE (D).

Giving the Sizes of Pipe which should be used in practice for Acetylene
Mains when the fall of pressure in the Main is not to exceed 0.5 inch,
(Based on Morel's formula.)

____________________________________________________________________
| | |
| Cubic feet | |
| of | |
| Acetylene | Diameters of Pipe to be used up to the lengths stated.|
| which the | |
| Main is | |
| required |_______________________________________________________|
| to pass | | | | | | | | |
| in One | 3/4 | 1 | 1-1/4| 1-1/2| 1-3/4| 2 | 2-1/2| 3 |
| Hour | inch.| inch.| inch.| inch.| inch.| inch.| inch.| inch.|
|____________|______|______|______|______|______|______|______|______|
| | | | | | | | | |
| |Miles.|Miles.|Miles.|Miles.|Miles.|Miles.|Miles.|Miles.|
| 10 | 5.05 | ... | ... | ... | ... | ... | ... | ... |
| 25 | 0.80 | 2.45 | 6.15 | ... | ... | ... | ... | ... |
| 50 | 0.20 | 0.60 | 1.50 | 3.30 | 6.45 | ... | ... | ... |
| 100 | 0.05 | 0.15 | 0.35 | 0.80 | 1.60 | 4.95 |12.30 | ... |
| 200 | ... | 0.04 | 0.09 | 0.20 | 0.40 | 1.20 | 3.05 |12.95 |
| 300 | ... | ... | 0.04 | 0.09 | 0.18 | 0.55 | 1.35 | 5.75 |
| 400 | ... | ... | ... | 0.05 | 0.10 | 0.30 | 0.75 | 3.25 |
| 500 | ... | .. | ... | 0.03 | 0.06 | 0.20 | 0.50 | 2.05 |
| 750 | ... | ... | ... | ... | 0.03 | 0.08 | 0.20 | 0.80 |
| 1100 | ... | ... | ... | ... | ... | 0.05 | 0.12 | 0.50 |
| 1500 | ... | ... | ... | ... | ... | 0.02 | 0.05 | 0.23 |
| 2000 | ... | ... | ... | ... | ... | ... | 0.03 | 0.13 |
| 2500 | ... | ... | ... | ... | ... | ... | 0.02 | 0.08 |
| 5000 | ... | ... | ... | ... | ... | ... | ... | 0.03 |
|____________|______|______|______|______|______|______|______|______|

TABLE (E).

Giving the Sizes of Pipe which should be used in practice for Acetylene
Mains when the fall of pressure in the Main is not to exceed 1.0 inch.
(Based on Morel's formula.)

__________________________________________________________________
| | |
| Cubic feet | |
| of | |
| Acetylene |Diameters of Pipe to be used up to the lengths stated|
| which the | |
| Main is | |
| required |_____________________________________________________|
| to pass | | | | | | | | | |
| in One | 3/4 | 1 |1-1/4|1-1/2|1-3/4| 2 |2-1/2| 3 | 4 |
| Hour |inch.|inch.|inch.|inch.|inch.|inch.|inch.|inch.|inch.|
|____________|_____|_____|_____|_____|_____|_____|_____|_____|_____|
| | | | | | | | | | |
| |Miles|Miles|Miles|Mile.|Miles|Miles|Miles|Miles|Miles|
| 10 | 2.40|10.13|30.90| ... | ... | ... | ... | ... | ... |
| 25 | 0.38| 1.62| 4.94|12.30| ... | ... | ... | ... | ... |
| 50 | 0.09| 0.40| 1.23| 3.07| 6.65|12.96| ... | ... | ... |
| 100 | 0.02| 0.10| 0.30| 0.77| 1.66| 3.24| 9.88| ... | ... |
| 200 | ... | 0.02| 0.07| 0.19| 0.41| 0.81| 2.47| 6.15| ... |
| 300 | ... | 0.01| 0.03| 0.08| 0.18| 0.36| 1.09| 2.73|11.52|
| 400 | ... | ... | 0.0 | 0.05| 0.10| 0.20| 0.61| 1.53| 6.48|
| 500 | ... | ... | 0.0 | 0.03| 0.06| 0.13| 0.39| 0.98| 4.14|
| 750 | ... | ... | ... | 0.01| 0.03| 0.05| 0.17| 0.43| 1.84|
| 1000 | ... | ... | ... | ... | 0.01| 0.03| 0.10| 0.24| 1.03|
| 1500 | ... | ... | ... | ... | ... | 0.01| 0.01| 0.11| 0.46|
| 2000 | ... | ... | ... | ... | ... | ... | 0.02| 0.06| 0.26|
| 2500 | ... | ... | ... | ... | ... | ... | 0.01| 0.04| 0.16|
| 5000 | ... | ... | ... | ... | ... | ... | ... | 0.01| 0.04|
|____________|_____|_____|_____|_____|_____|_____|_____|_____|_____|



CHAPTER VIII

COMBUSTION OF ACETYLENE IN LUMINOUS BURNERS--THEIR DISPOSITION

NATURE OF LUMINOUS FLAMES.--When referring to methods of obtaining
artificial light by means of processes involving combustion or oxidation,
the term "incandescence" is usually limited to those forms of burner in
which some extraneous substance, such as a "mantle," is raised to a
brilliant white heat. Though convenient, the phrase is a mere convention,
for all artificial illuminants, even including the electric light, which
exhibit a useful degree of intensity depend on the same principle of
incandescence. Adopting the convention, however, an incandescent burner
is one in which the fuel burns with a non-luminous or atmospheric flame,
the light being produced by causing that flame to play upon some
extraneous refractory body having the property of emitting much light
when it is raised to a sufficiently high temperature; while a luminous
burner is one in which the fuel is allowed to combine with atmospheric
oxygen in such a way that one or more of the constituents in the gas
evolves light as it suffers combustion. From the strictly chemical point
of view the light-giving substance in the incandescent flame lasts
indefinitely, for it experiences no change except in temperature; whereas
the light-giving substance in a luminous flame lasts but for an instant,
for it only evolves light during the act of its combination with the
oxygen of the atmosphere. Any fluid combustible which burns with a flame
can be made to give light on the incandescent system, for all such
materials either burn naturally, or can be made to burn with a non-
luminous flame, which can be employed to raise the temperature of some
mantle; but only those fuels can be burnt on the self-luminous system
which contain some ingredient that is liberated in the elemental state in
the flame, the said ingredient being one which combines energetically
with oxygen so as to liberate much local heat. In practice, just as there
are only two or three substances which are suitable for the construction
of an incandescent mantle, so there is only one which renders a flame
usefully self-luminous, viz., carbon; and therefore only such fuels as
contain carbon among their constituents can be burnt so as to produce
light without the assistance of the mantle. But inasmuch as it is
necessary for the evolution of light by the combustion of carbon that
that carbon shall be in the free state, only those carbonaceous fuels
yield light without the mantle in which the carbonaceous ingredient is
dissociated into its elements before it is consumed. For instance,
alcohol and carbon monoxide are both combustible, and both contain
carbon; but they yield non-luminous flames, for the carbon burns to
carbon dioxide in ordinary conditions without assuming the solid form;
ether, petroleum, acetylene, and some of the hydrocarbons of coal-gas do
emit light on combustion, for part of their carbon is so liberated. The
quantity of light emitted by the glowing substance increases as the
temperature of that substance rises: the gain in light being equal to the
fifth or higher power of the gain in heat; [Footnote: Calculated from
absolute zero.] therefore unnecessary dissipation of heat from a flame is
one of the most important matters to be guarded against if that flame is
to be an economical illuminant. But the amount of heat liberated when a
certain weight (or volume) of a particular fuel combines with a
sufficient quantity of oxygen to oxidise it wholly is absolutely fixed,
and is exactly the same whether that fuel is made to give a luminous or a
non-luminous flame. Nevertheless the atmospheric flame given by a certain
fuel may be appreciably hotter than its luminous flame, because the
former is usually smaller than the latter. Unless the luminous flame of a
rich fuel is made to expose a wide surface to the air, part of its carbon
may escape ultimate combustion; soot or smoke may be produced, and some
of the most valuable heat-giving substance will be wasted. But if the
flame is made to expose a large surface to the air, it becomes flat or
hollow in shape instead of being cylindrical and solid, and therefore in
proportion to its cubical capacity it presents to the cold air a larger
superficies, from which loss of heat by radiation, &c., occurs. Being
larger, too, the heat produced is less concentrated.

It does not fall within the province of the present book to discuss the
relative merits of luminous and incandescent lighting; but it may be
remarked that acetylene ranks with petroleum against coal-gas,
carburetted or non-carburetted water-gas, and semi-water-gas, in showing
a comparatively small degree of increased efficiency when burnt under the
mantle. Any gas which is essentially composed of carbon monoxide or
hydrogen alone (or both together) burns with a non-luminous flame, and
can therefore only be used for illuminating purposes on the incandescent
system; but, broadly speaking, the higher is the latent illuminating
power of the gas itself when burnt in a non-atmospheric burner, the less
marked is the superiority, both from the economical and the hygienic
aspect, of its incandescent flame. It must be remembered also that only a
gas yields a flame when it is burnt; the flame of a paraffin lamp and of
a candle is due to the combustion of the vaporised fuel. Methods of
burning acetylene under the mantle are discussed in Chapter IX.; here
only self-luminous flames are being considered, but the theoretical
question of heat economy applies to both processes.

Heat may be lost from a flame in three several ways: by direct radiation
and conduction into the surrounding air, among the products of
combustion, and by conduction into the body of the burner. Loss of heat
by radiation and conduction to the air will be the greater as the flame
exposes a larger surface, and as a more rapid current of cold air is
brought into proximity with the flame. Loss of heat by conduction, into
the burner will be the greater as the material of which the burner is
constructed is a better conductor of heat, and as the mass of material in
that burner is larger. Loss of heat by passage into the combustion
products will also be greater as these products are more voluminous; but
the volume of true combustion products from any particular gas is a fixed
quantity, and since these products must leave the flame at the
temperature of that flame--where the highest temperature possible is
requisite--it would seem that no control can be had over the quantity of
heat so lost. However, although it is not possible in practice to supply
a flame with too little air, lest some of its carbon should escape
consumption and prove a nuisance, it is very easy without conspicuous
inconvenience to supply it with too much; and if the flame is supplied
with too much, there is an unnecessary volume of air passing through it
to dilute the true combustion products, which air absorbs its own proper
proportion of heat. It is only the oxygen of the air which a flame needs,
and this oxygen is mixed with approximately four times its volume of
nitrogen; if, then, only a small excess of oxygen (too little to be
noticeable of itself) is admitted to a flame, it is yet harmful, because
it brings with it four times its volume of nitrogen, which has to be
raised to the same temperature as the oxygen. Moreover, the nitrogen and
the excess of oxygen occupy much space in the flame, making it larger,
and distributing that fixed quantity of heat which it is capable of
generating over an unnecessarily large area. It is for this reason that
any gas gives so much brighter a light when burnt in pure oxygen than in
air, (1) because the flame is smaller and its heat more concentrated, and
(2) because part of its heat is not being wasted in raising the
temperature of a large mass of inert nitrogen. Thus, if the flame of a
gas which naturally gives a luminous flame is supplied with an excess of
air, its illuminating value diminishes; and this is true whether that
excess is introduced at the base of the actual flame, or is added to the
gas prior to ignition. In fact the method of adding some air to a
naturally luminous gas before it arrives at its place of combustion is
the principle of the Bunsen burner, used for incandescent lighting and
for most forms of warming and cooking stoves. A well-made modern
atmospheric burner, however, does not add an excess of air to the flame,
as might appear from what has been said; such a burner only adds part of
the air before and the remainder of the necessary quantity after the
point of first ignition--the function of the primary supply being merely
to insure thorough admixture and to avoid the production of elemental
carbon within the flame.

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