Short answers, pulled from the story.
A candle is an ignitable wick embedded in wax or another flammable solid substance such as tallow. When lit, heat melts and vaporizes a small amount of wax, which combines with oxygen to form a flame; the flame then melts more wax, which travels up the wick via capillary action to sustain continuous burning.
Candles have been used for over two millennia around the world. The earliest excavated Etruscan candlestick dates from the 7th century BC, and early records in China suggest candles were in use during the Qin dynasty before 200 BC.
French candle maker M. Cambaceres introduced the plaited wick soaked with mineral salts in 1825. When burned, this wick curves toward the outer edge of the flame and incinerates itself, eliminating the need for manual trimming.
Joseph Morgan, a pewterer from Manchester, England, patented a candle-making machine in 1834. It used a cylinder with a moveable piston to continuously eject molded candles as they solidified, producing about 1,500 candles per hour.
Paraffin wax is a bluish-white substance derived from coal and oil shales. James Young developed a commercially viable method of distilling it at Bathgate in West Lothian in the mid-1850s; by the end of the 19th century, candles were made primarily from paraffin wax and stearic acid.
According to the National Fire Protection Association, candles are a leading source of residential fires in the United States. Almost 10 percent of civilian fire injuries and 6 percent of fire fatalities in the US are attributed to candles.