Page:Works of Jules Verne - Parke - Vol 6.djvu/42

 shore, glass-wort, ficoides, and all those fucaceæ which form wrack. A large quantity of these plants was collected, first dried, then burnt in holes in the open air. The combustion of these plants was kept up for several days, and the result was a compact gray mass, which has been long known under the name of "natural soda." This obtained, the engineer treated the fat with soda, which gave both a soluble soap and that neutral substance glycerine.

But this was not all. Cyrus Harding still needed, in view of his future preparation, another substance, azote of potash, which is better known under the name of salt of nitre, or of saltpetre. He could have manufactured this substance by treating the carbonate of potash, which would be easily extracted from the cinders of the vegetables, by azotic acid. But this acid was wanting, and he would have been in some difficulty, if nature had not happily furnished the saltpetre, without giving them any other trouble than that of picking it up. Herbert found a vein of it at the foot of Mount Franklin, and they had nothing to do but purify this salt

These different works lasted a week. They were finished before the transformation of the sulphuret into sulphate of iron had been accomplished. During the following days the settlers had time to construct a furnace of bricks of a particular arrangement, to serve for the distillation of the sulphate of iron when it had been obtained. All this was finished about the i8th of May, nearly at the time when the chemical transformation terminated. Gideon Spilett, Herbert, Neb, and Pencroft, skillfully directed by the engineer, had become most clever workmen. Before all masters, necessity is the one most listened to, and who teaches the best.

When the heap of pyrites had been entirely reduced by fire, the result of the operation, consisting of sulphate of iron, sulphate of alumina, flint, remains of coal, and cinders, was placed in a basin full of water. They stirred this mixture, let it settle, then decanted it, and obtained a clear liquid, containing in solution sulphate of iron and sulphate of alumina, the other matters remaining solid since they are insoluble. Lastly, this liquid being partly evaporated, crystals of sulphate of iron were deposited, and the not