MECHANICS AND USEFUL ARTS. 107 



a very hard body, called stearic acid, a liquid termed olcic acid, and a 

 white, sirupy body, which acts as a base to the other two. Now these three 

 companions agree admirably in nature, but the moment art attempts to con- 

 vert them to her own purposes, in the formation of candles, a little difficulty 

 arises; the glycerine turns out to be the slow man of the party; like many 

 good men and true, its illuminating power is found to be greatly deficient to 

 that of the company it is in, and hence its ejection is voted by the scientific 

 candle-maker. Not long since, this was performed by the process termed 

 lime saponification. By this method, cream of lime was intimately mixed 

 with the fatty matter to be acted upon, and the principle of chemical affini- 

 ties coming into play, the different ingredients, like the dancers in a certain 

 coquettish wait/, forsook each other for new comers; thus the stearic and 

 the oleic acids waltzed off with the lime, leaving the glycerine by itself. No 

 sooner, however, was this arrangement completed, than it was broken up by 

 the introduction of strong sulphuric acid, which in its turn waltzed away 

 with the lime, leaving the fat acids free. This was an expensive process, 

 however, inasmuch as, independently of the cost of the lime and sulphuric 

 acid, the stearic acid obtained was comparatively small in quantity, and the 

 whole of the glycerine was wasted. The next step in the process is known 

 as the sulphuric acid saponification, the fat acids being exposed to sulphuric 

 acid, at a temperature of 350 Fahrenheit. By this process, the glycerine is 

 decomposed, the fats are changed into a dark, hard, pitchy mass, the result 

 of the charring of the glycerine and coloring matters, its final purification 

 being effected in a still, from which the air is excluded by the pressure of 

 superheated steam. In 18-34, this process was brought to its present perfect 

 state, by passing this superheated steam directly into the neutral fat, by 

 which means it was resolved into glycerine and fat acids, the glycerine dis- 

 tilling over in company, but no longer combined with them. This was an 

 immense step gained, inasmuch as the glycerine, thus for the first time 

 obtained pure, and in lagre quantities, was raised from being a mere refuse 

 product which the candle-maker made every effort to destroy, into a most 

 important body, of great use in medicine and the arts ; indeed, like gutta- 

 percha, or vulcanized India-rubber, it is no doubt destined to play a great 

 part in the affairs of the world, and is far more valuable than its companion 

 bodies, the stearic and oleic acids. We may here mention that it is the 

 presence of this very glycerine in the old mould-candle, and in the still exist- 

 ing "dip," which produces the insufferable smell of the candle-snuff. A 

 candle, when blown out, exposes the smouldering wick to the action of the 

 atmosphere, and the glycerine distills away in the smoke. Yet here we see 

 as much as six tons distilling at one time, in one room, without the slightest 

 smell, in consequence of the process taking place in a vacuum. Imagine, 

 good reader, what would be your sensations sniffing at six tons of the 

 concentrated essence of candle-snuff! 



The two acids, the hard stearic and the fluent oleic, have still to be sepa- 

 rated, as it is only the former which is, from its high melting point, calcu- 

 lated to form the true candle material. The cooled fats, forming a thick, 

 lard-like substance, having been cut in appropriate slices by means of a 

 revolving cutter, are then, by an ingenious labor-saving appai-atus, spread 

 upon the surfaces of cocoa-nut mats, which are taken away in trucks to the 

 press-room. In the press-room these piles are subjected to hydraulic pres- 

 sure, which slowly squeezes out the oleic acid, leaving the stearic acid behind, 

 in the form of thin, hard, white cakes. These are remelted. The arrange- 

 ment by which the melting process is carried on is novel in the extreme. 



