The Stearine Candles, so much in use of late, are made of what
chemists call “stearic acid.” It is extracted from tallow by the
following process:--The fat is first melted, then boiled with
water and quick lime; the lime forms a solid insoluble soap with
the stearic acid of the fat. This, when cold, is dug out of the
cistern and separated from the watery parts; it is then melted in
a wooden cistern by means of perforated iron pipes, through which
steam passes; the steam not only melts it, but condenses and runs
to the bottom, thoroughly washing it; it is again allowed to cool,
separated when it is mixed, stirred well with sulphuric acid and a
large quantity of water, and allowed to settle. This separates all
the lime, which settles to the bottom, leaving the stearine floating
on the top, from whence, when cold, it is taken and again well
washed with steam. The mass, after cooling, is cut into shavings by
a machine consisting of a wheel, having knives attached to its edge;
the shavings are put into hair-cloth bags and subjected to the most
powerful pressure by means of the hydraulic press; each hair-cloth
bag having a warm iron plate interposed between it and the next bag.
The oily parts of the mass are, by these means, all pressed out; the
remainder is again cut up and a second time pressed, leaving the pure
stearine, white and crystalline like spermaceti.