Melt the wax in a jar, and put into it powdered nitrate of soda (Chili saltpetre) in the proportion of 1 oz. to the lb. of wax; afterwards add, by degrees, 2 oz. to the lb. of sulphuric acid, diluted with 10 times its weight of water, keeping the wax warm and stirring the while. Let it stand a short time, and then fill up the jar with hot water, and allow the whole to cool. The wax should then be white. Afterwards wash with water to remove any nitric acid that may remain, as it would make the wax yellow.
Melt the wax with about 3 per cent, of water in a bright copper vessel, preferably heated by steam, and when the whole is liquid, and has boiled for a few minutes, withdraw the heat. Then sprinkle over it some oil of vitriol in the proportion of 3 oz. or 4 oz. (fluid) to every cwt. of wax. Be careful in doing this, as if done carelessly the melted wax will froth up and boil over. The oil of vitriol should be scattered over the whole surface. Cover it over, and allow it to settle. Then skim it gently with a hot ladle and bale it into vessels to cool. Take care not to disturb the sediment. To bleach the was, expose it in thin flakes to the action of the sun, wind, and rain. Sometimes it is advisable to change the surface exposed by remelting it, and again making it into thin flakes.
Wax for candle-making is bleached by being melted in hot water or by steam in a wooden or tinned- copper vessel. It is allowed to settle, and the waxy superstratum is run off while fluid into a wooden trough, having a row of perforations in the bottom, by which it is distributed upon horizontal wooden cylinders revolving with their lower portions surrounded by cold water. The ribbons or fibres made in this way are exposed to the bleaching action of the atmosphere and sunlight, being frequently moistened and turned over during the process. It is necessary to guard against wind, which might scatter the shreds; hence large cloth covers are kept in readiness. The operation is continued till the wax becomes perfectly white. It is usually conducted in Britain between April and September, the weather not being propitious at other seasons. In France, it is customary to add a little cream of tartar or alum to the water in which the wax is melted, whereby the bleaching is much curtailed. Bleaching agents like chlorine render wax unfit for candle-making.
Paraffin wax is treated by mixing with a little strong sulphuric acid and heating to 150 ° C. This has the effect of charring the colouring matter, but does not injure the paraffin. After being allowed to cool, water is added and the whole boiled. When cool the wax forms a cake on the surface, which is then rinsed and dried. Filtering through animal charcoal, in a steam jacketed pan, produces an excellent colourless product.