human
You see much must still be done to this stuff before it comes out white, he said.
gpt
We squeeze the liquid through a series of filter bags and also send it through other filters filled with black bone coal.
human
What is black bone coal?
gpt
Bone coal is a product made by burning and pulverizing the large bones left at the abbatoirs until a coarse-grained black powder not unlike emery sand is made; if this is not allowed to become too fine with using it is an excellent sugar filter. In fact, strangely enough, nothing has ever been found to take its place, and it has become a necessary but expensive agency employed in every sugar refinery. Quantities of it are used; in our refinery alone we have about a hundred bone coal filters and each one holds thirty tons of black bone coal. That will give you some idea how much of it is needed. We get nothing back on it, either, for in the process of using it becomes finer, and after that it is good for nothing unless, perhaps, to be made into cheap shoe-dressing. Unlike many of the other industries sugar refining has no by-products; by that I mean nothing on which the manufacturer may recover money. On the contrary in the leather business, for example, almost every scrap of material can either be utilized or sold for cash; odds and ends of the hides go into glue stock, small bits of leather are made into heel-taps or hardware fittings. But in refining cane-sugar there is nothing to be turned back into money to reimburse the manufacturer for his outlay. What isn't sugar is dead loss.