The dogs peered eagerly in at the door, having followed the stranger with the liveliest curiosity. Towse, bolder than the rest, entered intrepidly with a nonchalant air and a wagging tail, for he and Rufe, having failed to find Birt, had just returned home. The small boy paused on the threshold in amazed recognition of the old gentleman who had occasioned him such a fright that day down the ravine. The professor gesticulated a great deal as he bent over the fire and gave Birt directions, and, with his waving hands and the glow on his hoary hair and beard, he looked like some fantastic sorcerer. Somehow Rufe was glad to see the familiar countenances of Pete and Joe, and was still more reassured to note that his mother was quietly standing beside the table, as she stirred the batter for bread in a wooden bowl. Tennessee had pressed close to Birt, her chubby hand clutching his collar as he knelt on the hearth. He held above the glowing coals a long fire shovel, on which the pulverized mineral had been placed, and his eyes were very bright as he earnestly watched it. "If it is gold," said the old man, "a moderate heat will not affect it." The shovel was growing hot. The live coals glowed beneath it. The breath of the fire stirred Tennessee's flaxen hair. And Birt's dilated eyes saw the yellow particles still glistening unchanged in the centre of the shovel, which was beginning to redden. CHAPTER XI. Suddenly--was the glistening yellow mineral taking fire? It began to give off sulphurous fumes. And drifting away with them were all Birt's golden visions and Nate's ill-gotten wealth--ending in smoke! The sulphurous odor grew stronger. Even Towse stopped short, and gazed at the shovel with a reprehensive sniff. "Ker-shoo!" he sneezed. And commenting thus, he turned abruptly and went hastily out, with a startled look and a downcast tail. His sneeze seemed to break the spell of silence that had fallen on the little group. "It be mighty nigh bodaciously changed ter cinders!" exclaimed Birt, staring in amaze at the lustreless contents of the shovel from which every suggestion of golden glimmer had faded. "What do it be, ef 'tain't gold?" "Iron pyrites," said the professor. "'Fools' gold,' it is often called." He explained to Birt that in certain formations, however, gold is associated with iron pyrites, and when the mineral is properly roasted, this process serving to expel the sulphur, the fine particles of gold are found held in the resulting oxide of iron. But the variety of the mineral discovered down the ravine he said was valueless, unless occurring in vast quantities, when it is sometimes utilized in the production of sulphur. "I wonder," Birt broke out suddenly, "if the assayer won't find no gold in them samples ez Nate sent him." The professor laughed. "The assayer will need the 'philosopher's stone' to find gold in any samples from this locality."