This playful mood comes out, also, in one or two anecdotes which are told of him, when his fame was established. For instance, an old lady friend being much troubled by some rancid butter, thought that she had hit upon a method of improving it, which she did by mixing with it a quantity of soda, she having a somewhat high opinion of the purifying virtues of that alkali, although, it is to be presumed, she little suspected the uses to which it was applied in the manufactures. By this addition of soda, she triumphantly claimed that her butter "was greatly improved." One evening, when Professor Faraday called upon her, the old lady produced a sample of her "improved" butter. A merry laugh rang out from the philosopher's lips as he exclaimed, "Well done, Mrs. W., you have improved your bad butter into very indifferent _soap_!" Good-humoured and good-natured as Faraday habitually was, he did not like to be worried unnecessarily over unimportant matters; and willing as he was to place even his invaluable time at the disposal of almost anyone who claimed his attention, he had no patience with persons who came to him thoughtlessly, as the following story shows: A young man called on him one morning, and with an air of great importance confided to him the result of some original researches in electrical philosophy. "And pray," asked the professor, taking down a volume of Ree's _Cyclopoedia_, "did you consult this, or any elementary work, to learn whether your discovery had been anticipated?" The young man replied in the negative. "Then why do you come to waste my time about well-known facts that were published forty years ago?" "Sir," said the visitor in self-excuse, and hoping to flatter the philosopher, "I thought I had better bring the matter to headquarters immediately." "All very well for you, but not so well for headquarters," replied the professor sharply, and he forthwith set his visitor to read the article in the _Cyclopoedia_. Yet another story is told of a grave old gentleman who once waited upon Faraday that he might show to him "a new law of physics." The gentleman asked for a jug of water and a tumbler; they were brought, and he then produced a cork. "You will be pleased to observe," he then said, "how persistently this cork clings to the side of the glass when the vessel is half-filled." "Just so," replied the professor. "But now," continued the discoverer of a new law of physics, "mark what happens when I fill the glass to the brim. There! you see the cork flies to the centre--positively repelled by the sides!"