Idiom of the Day
when it comes to (something)
speaking about something
When it comes to sports, my friend is a very knowledgeable person.
Artificial Candle Lighting
Candles were originally made by dipping a wick into melting tallow, withdrawing it, allowing the adhered tallow to harden, and repeating the dipping until a satisfactory thickness was obtained. The more modern method consists in pouring a fatty preparation into a mold, at the center of which a wick has been placed.
The wick, when lighted, burns for a brief interval with a faint, uncertain light; almost immediately, however, the intensity of the light increases and the illumination remains good as long as the candle lasts. The heat of the burning tallow melts more of the tallow near it, and this liquid fat is quickly sucked up into the burning wick. The heat of the flame is sufficient to change most of this liquid into a gas, that is, to vaporize the liquid, and furthermore to set fire to the gas thus formed. These heated gases burn with a bright yellow flame.