After considerable
work upon the subject, I have succeeded in doing this by a very
delicate process of analysis, and I now wish to lay some of my results
before you.
If a cold substance, metal or non-metal, be placed in a flame, whether
it be luminous or non-luminous, it will be observed that there is a
clear space, in which no combustion is taking place, formed round the
cool surface, and that as the body gets heated so this space gets less
and less until, when the substance is at the same temperature as the
flame itself, there is contact between the two. Moreover, when a
luminous flame is employed in this experiment the space still exists
between the cool body and the flame, but you also notice that the
luminosity is decreased over a still larger area although the flame
exists.
This meaning that, in immediate contact with the cold body, the
temperature is so reduced that the flame cannot exist, and so is
extinguished over a small area; while over a still larger space the
temperature is so reduced that it is not hot enough to bring about
decomposition of the heavy hydrocarbons with liberation of carbon to
the same extent as in hotter portions of the flame. Now, inasmuch as
when water is heated or boiled in an open vessel, the temperature
cannot rise above 100 deg.C., and as the temperature of an ordinary flame
is over 1,000 deg.C., it is evident that the burning gas can never be in
contact with the bottom of the vessel, or, in other words, the gas is
put out before combustion is completed, and the unburned gas and
products of incomplete combustion find their way into the air and
render it perfectly unfit for respiration.
Pages:
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121