Page:Popular Science Monthly Volume 42.djvu/716

This page has been proofread, but needs to be validated.

Annales de Chimic. This apparatus, according to Prof. Sillirnan, was the earliest and most remarkable of Dr. Hare's original contributions to science. It revealed to the chemical student a source of artificial power far transcending anything he had ever known before; and this, though the facts on which it was based were not unknown.

Lavoisier had directed a jet of oxygen on charcoal and had burned the elements of water together; but even he, and in the face of these experiments, had failed to comprehend the power of this heating apparatus, and it was left for the acumen of Hare to demonstrate it and make it practically applicable. The author of the biography in the American Journal of Science says of it, "In our view, Dr. Hare's merit as a scientific philosopher is more clearly established upon this discovery than upon any other of the numerous contributions he has made to science." Dr. Hare's original experiments were repeated in 1802 and 1803 in the presence of Dr. Priestley and Messrs. Sillirnan, Woodhouse, and others. In recognition of the discovery, Dr. Hare received the Rumford medal from the American Academy of Science at Boston. An attempt was afterward made, in 1819, by Dr. Clarke, of Edinburgh, to rob him of the credit of this discovery; and though he showed that the oxyhydrogen apparatus had been before the public several years, no attention was paid to his protests. The calcium and Drummond lights also furnish instances of most important applications of Dr. Hare's invention, in which no reference is made to him. He himself led the way to these devices by constructing an apparatus on a gigantic scale, with large vessels of wrought iron, capable of sustaining the pressure of the Fairmount Water Works, with which he was able to fuse at one operation nearly two pounds of platinum, with a resultant production of metal greatly purified.

He devoted much labor and skill to the construction of new and improved forms of the voltaic pile; "and it is easy to show," Prof. Sillirnan says, "that owing to his zeal and skill in this department of physics American chemists were enabled to employ with distinguished success, the intense powers of extended series of voltaic couples long in advance of the general use of similar contrivances in Europe."

In 1816 Dr. Hare constructed an instrument called the calorimeter, in which great extent of surface was obtained by combining many large plates of zinc and copper into one series, and plunging the whole at once into a tank of dilute acid. Great magnetic and heating effects were obtained with this instrument, and it was many years before any other voltaic apparatus was constructed in which the movement of so great a volume of heat was attained with so low a projectile or intensive force. By it large rods of iron or platinum were ignited and fused with splendid ex-