Chemistry in the Service of Man

pped in olive oil which burned with but a feeble light even in its vase of finest workmanship. Think also of the old guttering candle, with its constant need of "snuffing," and you will understand how great has been the advance in the direction of artificial illumination; and practically the whole of this advance has taken place since the beginning of the nineteenth century. The production of light depends in all cases, with the exception of electric light, on the process of combustion in air, and it is therefore only what one would expect, that man first made use of those naturally occurring substances and materials which can be burned without requiring previous special treatment. Thus, the vegetable oils, such as olive oil and rape-seed oil, furnished, from a very early period, the main light-giving material; and at a later date, the need of a vessel to contain the oil was done away with by using the solid animal fats, in the form of candles. For the earliest candles a solid animal fat was employed, such as ox-fat or tallow, and the candle was made by repeatedly dipping the wick, which was first made from the pith of the rush and later of cotton fibres, into the melted tallow. From the manner in which they were made, these candles were called dips. But early in the nineteenth century, the advance of chemical knowledge enabled man to improve upon nature ; the natural was superseded by the artificial, and the task of the careful housewife, who used to save ...