Robert Hare, an American physicist, born in Philadelphia, Jan. 17, 1781, died there, May 15, 1858. His father, an English emigrant, settled in Philadelphia, and established there an extensive brewery, and his son in early life managed the business. His tastes, however, led him to scientific pursuits. He attended the courses of lectures on chemistry and physical sciences, and before he was 20 years of age joined the chemical society of Philadelphia, to which in 1801 he communicated a description of his important scientific invention, the oxyhydrogen blowpipe, which he then called the hydrostatic blowpipe, and which was afterward named by Prof. Silliman the compound blowpipe. (See Blowpipe.) At this period the subject of combustion was very imperfectly understood, and even Lavoisier, who had discovered that heat sufficiently intense to fuse alumina might be obtained by directing a jet of oxygen upon charcoal, and who had burned the elements of water together to produce this fluid, failed to discover that by this union of hydrogen and oxygen in combustion the most intense degree of heat known might be obtained. By means of this apparatus Hare was the first to render lime, magnesia, iridium, and platinum fusible in any considerable quantity.

In addition to these discoveries he first announced that steam is not condensable when combined in equal parts with the vapor of carbon. In 1818 he was appointed professor of chemistry in the medical school of the university of Pennsylvania, and continued in this office till his resignation in 1847. His course of instruction was marked by the originality of his experiments and of the apparatus he employed. His instruments, often designed and sometimes made by himself, were always of large dimensions and of the most perfect plans; no expense nor personal labor being spared to render every piece of apparatus as complete as possible. The great collection which he accumulated he bestowed, after resigning his office in the university, upon the Smithsonian institution. One of the most useful small instruments of his invention is the valve cock or gallows screw, by means of which perfectly air-tight communication is made between cavities in separate pieces of apparatus. To his zeal and skill in devising and constructing improved forms of the voltaic pile, American chemists are indebted for the success they attained in applying the intense powers of extended series of voltaic couples long in advance of the general use of similar combinations in Europe. In 1816 he invented the calorimotor, a form of battery by which a large amount of heat is produced with little intensity.

With the modified form of it called the deflagrator, devised in 1820, Prof. Silliman succeeded in 1823 in volatilizing and fusing carbon. The perfection of these forms of apparatus was acknowledged by Faraday, who adopted them in preference to any forms he could devise. It was with these batteries that the first application of voltaic electricity to blasting under water was made. This was in 1831, and the experiments were made under the direction of Dr. Hare. (See Blasting.) He contributed numerous papers to the " American Journal of Science," and other periodicals, and published "Brief View of the Policy and Resources of the United States " (1810), "Chemical Apparatus and Manipulations'1 (1886), and "Compendium of the Course of Chemical Instruction in the Medical Department of the University of Pennsylvania." In his later years he became a believer in spiritual manifestations, and wrote "Spiritualism Scientifically Demonstrated " (1855).