damp

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damp,

in mining, any mixture of gases in an underground mine, especially oxygen-deficient or noxious gases. The term damp probably is derived from the German dampf, meaning fog or vapor. Several distinct types of damp are recognized. Firedamp is methanemethane
, CH4, colorless, odorless, gaseous saturated hydrocarbon; the simplest alkane. It is less dense than air, melts at −184°C;, and boils at −161.4°C;. It is combustible and can form explosive mixtures with air.
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 and other flammable gases, often mixed with air; it results from the decomposition of coal or other carbonaceous materials. Explosive mixtures of firedamp with air usually contain from 1% to 14% methane. The mixture of gases that remains after a firedamp explosion is called afterdamp; it consists chiefly of carbon dioxide and nitrogen. Chokedamp is any mixture of oxygen-deficient mine gases that causes suffocation. (In England, carbon dioxide is called chokedamp.) Several methods are used for detection of damps. The Davy safety lampsafety lamp,
oil lamp designed for safe use in mines and other places where flammable gases such as firedamp (see damp) may be present. Its invention (c.1816) is usually attributed to Sir Humphry Davy.
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 is one of the earliest detection devices. The color and height of the lamp flame indicate the amount of firedamp present; if the flame is extinguished, chokedamp is present. Canaries were formerly kept in mines; the birds are overcome by relatively small quantities of noxious gases, and their death warned the miners of the presence of damps. Special colorimetric detectors are now used. The methanometer is a special portable instrument used to detect firedamp.

damp

[damp]
(engineering)
To reduce the fire in a boiler or a furnace by putting a layer of damp coals or ashes on the fire bed.
(mining engineering)
A poisonous gas in a coal mine.
(physics)
To gradually diminish the amplitude of a vibration or oscillation.
References in classic literature ?
Now, when your weapons are dulled, your ardor damped, your strength exhausted and your treasure spent, other chieftains will spring up to take advantage of your extremity.
This incident damped the ingenuous youth's spirits, and no word of yea or nay could he be induced to utter during the rest of the drive.
The spirits of the company being somewhat damped by this embarrassing line of conduct on the part of their host, nothing more was said for a long time; but at length Mr Cobb took upon himself to remark, as he rose to knock the ashes out of his pipe, that he hoped Joe would thenceforth learn to obey his father in all things; that he had found, that day, he was not one of the sort of men who were to be trifled with; and that he would recommend him, poetically speaking, to mind his eye for the future.
There was a little mound of damped ashes on the top of the fire, and another little mound swept together under the grate, as there had been night and day for fifteen years.
That's acause they damped the straw afore they lit it in the chimbley to make 'em come down again,' said Gamfield; 'that's all smoke, and no blaze; vereas smoke ain't o' no use at all in making a boy come down, for it only sinds him to sleep, and that's wot he likes.
It was late in the afternoon when the four friends and their four-footed companion turned into the lane leading to Manor Farm; and even when they were so near their place of destination, the pleasure they would otherwise have experienced was materially damped as they reflected on the singularity of their appearance, and the absurdity of their situation.