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XVIII.—On the Colour of Steam under certain circumstances

Published online by Cambridge University Press:  17 January 2013

James D. Forbes Esq.
Affiliation:
Professor of Natural Philosophy in the University of Edinburgh.

Extract

In the end of May, or beginning of June last, I happened to stand near a locomotive engine on the Greenwich Railway, which was discharging a vast quantity of high-pressure steam by its safety-valve. I chanced to look at the sun through the ascending column of vapour, and was struck by seeing it of a very deep orange-red colour, exactly similar to that of dense smoke, or the colour imparted to the sun when viewed through a common smoked glass.

I did not pay much attention to the fact at the moment, nor attempt to vary the experiment; but, reflecting on it afterwards, it seemed to me not only as in itself very singular, but as still more extraordinary, because I had never heard of a property of steam which must have been witnessed by thousands of persons. Some months after (in the end of October), being on the Newcastle and Carlisle Railway, I resolved to verify the fact, which I had no difficulty in doing, and I farther discovered a very important modification of it. For some feet or yards from the safety-valve at which the steam blows off, its colour for transmitted light is the deep orange-red I have described.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1840

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References

page 371 note * The same may be observed, during the ordinary progress of the engine, in the steam thrown into the chimney, but the presence of smoke renders the experiment less satisfactory.

page 372 note * The experiments were performed at night.