to 807 deg. C.,
samples of the gas which issued when the heat was greatest were submitted
to chemical analysis, and their illuminating powers were determined. The
figures he gives are as follows:
I. II.
Per Cent. Per Cent.
Acetylene 70.0 69.7
Saturated hydrocarbons 11.3 11.4
Hydrogen 18.7 18.9
_____ _____
100.0 100.0
The average illuminating power of these mixed gases is about 126 candles
per 5 cubic feet, whereas that of pure acetylene burnt under good
laboratory conditions is 240 candles per 5 cubic feet. The product, it
will be seen, had lost almost exactly 50 per cent. of its value as an
illuminant, owing to the excessive heating to which it had been, exposed.
Some of the liquid hydrocarbons formed at the same time are not limpid
fluids like benzene, which is less viscous than water, but are thick oily
substances, or even tars. They therefore tend to block the tubes of the
apparatus with great persistence, while the tar adheres to the calcium
carbide and causes its further attack by water to be very irregular, or
even altogether impossible.
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