It is now time to turn to something stronger than water for more instances of chemical contradictions. The chemical action of certain poisons (the most powerful of all agents), upon the human frame, has plunged the faculty into a maze of paradoxes; indeed, there is actually a system of medicine, advancing in reputation, which is founded on the principle of contraries. The famous Dr. Hahnemann, who was born at Massieu in Saxony, was the founder of it, and, strange to say, medical men, who are notorious for entertaining contrary opinions, have not yet agreed among themselves whether he was a very great quack or a very great philosopher. Be this as it may, the founder of this system, which is called HOMOEOPATHY, when translating an article upon bark in Dr. Cullen's Materia Medica, took some of this medicine, which had for many years been justly celebrated for the cure of ague. He had not long taken it, when he found himself attacked with aguish symptoms, and a light now dawned upon his mind, and led him to the inference that medicines which give rise to the symptoms of a disease, are those which will specifically cure it, and however curious it may appear, several illustrations in confirmation of this principle were speedily found. If a limb be frost-bitten, we are directed to rub it with snow; if the constitution of a man be impaired by the abuse of spirituous liquors, and he be reduced to that miserable state of enervation when the limbs tremble and totter, and the mind itself sinks into a state of low muttering delirium, the physician to cure him must go again to the bottle and administer stimulants and opiates. It was an old Hippocratic aphorism that two diseases can not co-exist in the same body, wherefore, gout has actually been cured by the afflicted person going into a fenny country and catching the ague. The fatality of consumption is also said to be retarded by a common catarrh; and upon this very principle depends the truth of the old saying, that rickety doors hang long on rusty hinges. In other words, the strength of the constitution being impaired by one disease has less power to support the morbid action of another. We thus live in a world of apparent contradictions; they abound in every department of science, and beset us even in the sanctuary of domestic life. The progress of discovery has reconciled and explained the nature of some of them; but many baffle our ingenuity, and still remain involved in mystery. This much, however, is certain, that the most opposed and conflicting elements so combine together as to produce results, which are strictly in unison with the order and harmony of the universe. DESCENT INTO THE CRATER OF A VOLCANO.[18] BY REV. H.T. CHEEVER.