Glycerin a By-Product.
And when all has been extracted that you would think could be extracted, all the bits and scraps and scrapings and what not are put into a tank and cooked and cooked until all is dissolved that can be dissolved. The residual fat is skimmed off, and the last bit of glue, and the insoluble matter at the bottom of the tank, go for fertilizer, and then, in the packing-houses that don't know their business, the tank water is let run away. But there is much valuable nitrogenous matter in those waters which the first-rate packers utilize. And there is glycerin there.
In the old days the candle-makers who used palm-oil had their own troubles with glycerin. If a candle was blown out, the smoldering wick used to leave an offensive odor. It was the glycerin that caused this. Naturally, the only thing to do was to take it out of the candle, and the next thing was to get rid of it down the gulley into the creek. People complained, as people will; but what else was an honest chandler to do? Latterly they have been figuring on the matter, and some of them have come to the conclusion that they used to let as much as two thousand dollars' worth of glycerin get away from them every week.
In the last five years the soap-makers have learned that they can realize more money out of the glycerin than they can out of the soap they make. Some of this glycerin is refined, but the great part of the crude goes to the manufacturers of dynamite, which is nitroglycerin mixed with infusorial earth, so as to weaken it.
There is just as much acid after the glycerin is turned into nitroglycerin as there was before. After it is washed out the nitro is left apparently unchanged. It is not broken up, but it is on the edge of it. Give it a knock and it all flies to pieces at once so suddenly that it will loosen more dirt in a second than a hundred pick-and-shovel men could scoop out in a week.