CHEMICAL HISTORY OF A CANDLE 91 



cracked about and broken a great deal, yet when lighted it 

 goes on burning regularly, and the tallow resumes its natural 

 condition as soon as it is fused. 



Mr. Field, of Lambeth, has supplied me abundantly with 

 beautiful illustrations of the candle and its materials; I 

 shall therefore now refer to them. And, first, there is the 

 suet the fat of the ox Russian tallow, I believe, employed 

 in the manufacture of these dips, which Gay-Lussac, or some 

 one who intrusted him with his knowledge, converted into 

 that beautiful substance, stearin, which you see lying beside 

 it. A candle, you know, is not now a greasy thing like an 

 ordinary tallow candle, but a clean thing, and you may almost 

 scrape off and pulverize the drops which fall from it with- 

 out soiling any thing. This is the process he adopted :(*) 

 The fat or tallow is first boiled with quick-lime, and made 

 into a soap, and then the soap is decomposed by sulphuric 

 acid, which takes away the lime, and leaves the fat rear- 

 ranged as stearic acid, while a quantity of glycerin is pro- 

 duced at the same time. Glycerin absolutely a sugar, or a 

 substance similar to, sugar comes out of the tallow in this 

 chemical change. The oil is then pressed out of it ; and you 

 see here this series of pressed cakes, showing how beautifully 

 the impurities are carried out by the oil^ part as the pressure 

 goes on increasing, and at last you have left that substance, 

 which is melted, and cast into candles as here represented. 

 The candle I have in my hand is a stearin candle, made of 

 stearin from tallow in the way I have told you. Then here 

 is a sperm candle, which comes from the purified oil of the 

 spermaceti whale. Here, also, are yellow bee's-wax and re- 

 fined bee's-wax, from which candles are made. Here, too, is 

 that curious substance called paraffine, and some paraffine 

 candles, made of paraffine obtained from the bogs of Ireland. 



'The fat or tallow consists of a chemical combination of fatty acids with 

 glycerin. The lime unites with the palmitic, oleic, and stearic acids, and 

 separates the glycerin. After washing, the insoluble lime soap is decom- 

 posed with hot dilute sulphuric acid. The melted fatty acids thus rise as 

 an oil to the surface, when they are decanted. They are again washed and 

 cast into thin plates, which, when cold, are placed between layers of cocoa- 

 nut matting and submitted to intense hydraulic pressure. In this way the 

 soft pleic acid is squeezed out, while the hard palmitic and stearic acids 

 remain. These are farther purified by pressure at a higher temperature and 

 washing in warm dilute sulphuric acid, when they are ready to be made into 

 andles. These acids are harder and whiter than the fats from which they 

 were obtained while at the same time they are cleaner and more combustible: 



