While the priest toiled blowing the fire, the sweat running down his face with the heat, the wily canon drew out of his store a piece of beech wood.  In it he had made a cavity and inserted just an ounce of silver shavings and stopped up the hole with wax.  Now understand, friends, here and hereafter, that with foresight of what he meant to do, he had prepared all his cunning tricks and appliances.  Then with feigned solicitude, “Sir priest,” he said, “right well have you toiled, but still the fire burns not quite right as yet.  Let me try what I can do.  Wipe your face and rest you.”  The priest was only too glad of a rest, and while he wiped his face the canon stirred the fire and placed his piece of wood fairly over the mouth of the crucible.  Then as soon as the wood grew hot the wax melted—­as needs it must—­and the silver fell down into the vessel.  “That is right now,” said he; “let us rejoice and take a drink, for all shall now be well.”

The priest was delighted, good innocent man, suspecting nothing of the craft that was practised against him.  At length the canon said, “Come, let us go out to get some clay, with which to make a mould for our metal, and a bowl of water.  I will go with you, for I would not like you to think that I had played any tricks with this wonderful art.”  They fetched the water and clay, the canon fashioned the mould, poured in the metal and cast it into the water to cool.

Now what had really happened was this.  When mercury is heated in a crucible—­as perhaps all you gentlemen know, though in case you do not I must tell you to make my story plain—­it changes into a vapour like steam and disappears, but silver only melts and does not change otherwise.  So when the canon poured out the contents of the crucible into the mould, there was the silver all liquid and ready, but the mercury was gone.  Therefore in the cold water the liquid silver changed into a lump and was there for the priest to find, but the mercury had disappeared.  The canon knew all about this, but the priest understood nothing and was just watching in wonder.  “Now, sir priest,” said the canon, “put in your hand and see what you can find.”  The priest put in his hand and drew out the lump of shining silver.  “Ah,” said the canon, “let us make trial yet again.  Once is scarce a complete proof, and I should like you to understand this art thoroughly before we part.”

They took another ounce of the quicksilver and put it in the crucible.  The canon put in the powder and arranged the fire, but this time he had his silver shavings hidden in a long cane of which the end was stopped with wax as before.  He made pretence to stir the fire.  “It burns not as brightly as it should,” he said, “but I will make the flames leap up.”  And so, as he poked it, he melted the wax and let the silver fall into the crucible.  Once more they poured the metal into the mould and again the priest drew out a lump of silver.  “Yet a third time we will try,” said the canon, “and this time we will not use quicksilver but copper.  Send your servant for an ounce of it.”