The Romance of Modern Chemistry

FATS AND OILS for the curving over of the end of the wick would shift its lower portion out of the centre of the candle, tallow being such a plastic material. The end of the wick m a tallow dip keeps straight, and soon gets into the top of the flame, where it is charred, but cannot get enough oxygen for complete combustion; it interferes with the proper burning of the candle and the flame is rendered dull and smoky. From time to time, therefore, the tallow candle must be “snuffed”; that is, the end of the wick must be removed. When tallow is treated with high-pressure steam it is split up, or “hydrolysed,” to use the technical term, and the three acids mentioned above are liberated from the sway of the glycerine. At this stage they are crude and dark in colour, and are therefore subjected to dis- tillation in a current of superheated steam. The nearly colourless mixture of the purified acids obtained in this way is subjected to pressure, so that the liquid oleic acid is squeezed out; the remaining product, known as “ stearine/ and consisting mainly of stearic acid, is cast into candles in suitable moulds. Stearine does not melt below 160° Fahrenheit, so that candles made of this material will keep erect even in tropical countries. For use in temperate climates, candles are usually made of a mixture of stearine and paraffin wax, the latter being obtained in large quantities (about 24,000 tons a year) by the destructive distillation of Scottish shale. Candles are, as a matter of fact, made from paraffin wax alone, but they are rather soft and given to collapsing in hot weather. The tallow candle has been nearly ousted from the market by these modem com- petitors, but even yet the annual output of the former in this country amounts to a good many hundred tons 245