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Demos: 3B-02 Safety Lamp


A small quantity of ether is poured into a large glass vessel. A gas flame is brought into the vessel to show that the ether vapor is flammable. After the vapor is burned out (or snuffed with a lid), a small quantity of vapor is reintroduced into the vessel. A lighted miner’s lamp (Davy Lamp) is then placed in the vessel and the ether does not explode. The secret is in the copper gauze that surrounds the lamp. The gauze, being a good conductor of heat, keeps the temperature around the lamp below the ignition temperature of ether.

Directions: Pour the ether into the vessel. Strike a match, make sure it is well caught, and drop it into the vessel. There will be a big explosion of flame inside the vessel. (You can snuff out the flame by placing the flat lid over the vessel or you can just let it burn itself out.) Remove the holder, the glass chimney and the wire gauze from the lamp. Light the wick. (If the wick is too high, a very smoky flame will result. Trim the wick to reduce this.) Put the lamp back together in the proper order (gauze, glass chimney, outer holder). Pour the other bottle of ether into the vessel. Slowly lower the lamp into the vessel. It will not ignite the ether. To show that it really is ether, remove the lamp and drop a lighted match into the vessel, as before.

Suggestions for Presentation: You might start by talking about how mines often have explosive gases, somewhat like this ether. (Pick up the bottle and pour it into the vessel.) Then suggest that an open flame could spark an explosion (drop in match). Then ask what would happen if we placed this miner’s lamp in the ether. (Ask for volunteers!) Pour in the ether, place the lamp in the vessel while pretending to be frightened. There may be doubters about the second bottle. Was it really ether? Show them by dropping another match in the vessel.

You can supplement this demonstration by holding a wire gauze over the flame of a Bunsen burner. The flame will not pass through the gauze, even though the gas does.

Applications: Before electric lamps were invented, this lamp was the safety lamp for coal miners.

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Last Updated: May 9, 2016 11:44 AM

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