For two more years he went on experimenting without any satisfactory result, until the proceeds of his survey of the salt-marshes having become nearly spent, he was reduced to poverty again. But he resolved to make a last great effort; and he began by breaking more pots than ever. More than three hundred pieces of pottery covered with his compounds were sent to the glass-furnace; and thither he himself went to watch the results of the baking. Four hours passed, during which he watched; and then the furnace was opened. The material on _one_ only of the three hundred pieces of potsherd had melted, and it was taken out to cool. As it hardened, it grew white-white and polished! The piece of potsherd was covered with white enamel, described by Palissy as “singularly beautiful!” And beautiful it must no doubt have been in his eyes after all his weary waiting. He ran home with it to his wife, feeling himself, as he expressed it, quite a new creature. But the prize was not yet won—far from it. The partial success of this intended last effort merely had the effect of luring him on to a succession of further experiments and failures. In order that he might complete the invention, which he now believed to be at hand, he resolved to build for himself a glass-furnace near his dwelling, where he might carry on his operations in secret. He proceeded to build the furnace with his own hands, carrying the bricks from the brick-field upon his back. He was bricklayer, labourer, and all. From seven to eight more months passed. At last the furnace was built and ready for use. Palissy had in the mean time fashioned a number of vessels of clay in readiness for the laying on of the enamel. After being subjected to a preliminary process of baking, they were covered with the enamel compound, and again placed in the furnace for the grand crucial experiment. Although his means were nearly exhausted, Palissy had been for some time accumulating a great store of fuel for the final effort; and he thought it was enough. At last the fire was lit, and the operation proceeded. All day he sat by the furnace, feeding it with fuel. He sat there watching and feeding all through the long night. But the enamel did not melt. The sun rose upon his labours. His wife brought him a portion of the scanty morning meal,—for he would not stir from the furnace, into which he continued from time to time to heave more fuel. The second day passed, and still the enamel did not melt. The sun set, and another night passed. The pale, haggard, unshorn, baffled yet not beaten Palissy sat by his furnace eagerly looking for the melting of the enamel. A third day and night passed—a fourth, a fifth, and even a sixth,—yes, for six long days and nights did the unconquerable Palissy watch and toil, fighting against hope; and still the enamel would not melt.