Were candles expensive in medieval Europe? Family can use it?

This kind of candle was introduced from China during the Nara period (7 10 ~ 784). Compared with modern candles, ancient candles have many disadvantages. Li Shangyin, a poet in the Tang Dynasty, wrote a poem "How to Cut Candles in the West Window". Why do poets cut candles? At that time, the wick of the candle was made of cotton thread and stood upright in the center of the flame. Because it is impossible to burn out carbonization, it is necessary to cut off the remaining wick ends with scissors from time to time. This is undoubtedly a troublesome thing. 1820, a Frenchman, Jean Bessie, invented a wick made of three cotton threads, which made the wick loose naturally when burning, and the end just tilted to the outside of the flame, so it could burn completely. However, candles need further improvement. Its material is generally animal fat, which has many disadvantages. Chevelle and others solved this problem. 1809 From June to July, the French scientist Schaeffler received a letter from a textile factory, asking him to analyze and determine the composition of a soft soap sample they sent. He took this letter and thought for a long time, thinking: the study of soap seems to start with raw oil. In the experiment with very simple equipment at school, he studied all kinds of oils and fats needed in the saponification process. After a lot of experiments, he discovered the fact for the first time: in all oils and fats, regardless of their source, the content of fatty acids accounts for 95%, and the remaining 5% is glycerol generated in the saponification process. Through research, he found out the essence of saponification process, and at the same time made an important discovery: candles made of oil at that time, because there was glycerin in them, burned with smoke and smell. If stearic acid is used as a candle, it will not only burn brightly, but also have almost no black smoke and will not pollute the air. Schaeffler told Guy Wojciech Luczak about his findings and suggested that the two of them study how to solve the problem concretely. They saponify the oil with strong alkali, then decompose the soap with hydrochloric acid and take out stearic acid. This is a kind of white material, and it feels greasy. Candles made of it are soft and cheap. 1825, Schaeffler and Guy Lussac obtained the patent for producing paraffin wax stearin candles. The appearance of paraffin wax stearin candle opened a new era in the history of human lighting. Later, someone discovered a large oil field in North America, so a large amount of paraffin can be extracted from oil, so the ideal candle has been popularized and popularized all over the world.