It was then necessary to separate the glycerine from the fat by saponifying it.

Now, to obtain this result, it had to be treated either with soda or lime.

In fact, one or other of these substances, after having attacked the fat, would form a soap by separating the glycerine, and it was just this glycerine which the engineer wished to obtain.

There was no want of lime, only treatment by lime would give calcareous soap, insoluble, and consequently useless, while treatment by soda would furnish, on the contrary, a soluble soap, which could be put to domestic use.

Now, a practical man, like Cyrus Harding, would rather try to obtain soda.