he Mitchells, Silliman, and
Torrey, are well known as chemical philosophers; and Booth, Boye,
Chilton, Keating, Mather, R. Rogers, Seybert, Shepherd, and Vanuxen, as
_analysts_; and F. Bache, Webster, Greene, Mitchell, Silliman, and Hare,
as authors. In my native town of Northumberland, Pennsylvania, resided
two adopted citizens, most eminent as chemists and philosophers,
Priestley and Cooper. The latter, who was one of my own preceptors, was
greatly distinguished as a writer, scholar, jurist, and physician, as
well as a chemist. Priestley, although I do not concur in his peculiar
views of theology, was certainly one of the most able and learned of
ecclesiastical writers, and possessed also a mind most vigorous and
original. His discoveries in pneumatic chemistry have exceeded those of
any other philosopher. He discovered vital air, many new acids, chemical
substances, paints, and dyes. He separated nitrous and oxygenous airs,
and first exhibited acids and alkalies in a gaseous form. He ascertained
that air could be purified by the process of vegetation, and that light
evolved pure air from vegetables. He detected the powerful action of
oxygenous air upon the blood, and first pointed out the true theory of
respiration. The eudiometer, a most curious instrument for fixing the
purity of air, by measuring the proportion of oxygen, was discovered by
Dr. Priestley. He lived and died in my native town, universally beloved
as a man, and greatly admired as a philosopher. Chemistry has actively
advanced among us during the present century. Hare's compound blowpipe
came from his hand so perfect, in 1802, that all succeeding attempts of
Dr. Clark, of England, and of all others, in Europe and America, to
improve upon it or go beyond the effects produced, have wholly failed.
His mode of mixing oxygen and hydrogen gases, the instant before burning
them, was at once simple, effective, and safe. The most refractory
metallic and mineral substances yielded to the intense heat produced by
the flame of the blowpipe. In chemical analysis, the useful labors of
Keating, Vanuxen, Seybert, Booth, Clemson, Litton, and Moss, would fill
many volumes. In organic chemistry, the researches of Clark, Hare, and
Boye were rewarded by the discovery of a new ether, the most explosive
compound known to man. Mitchell's experiments on the penetration of
membranes by gases, and the ingenious extension of them by Dr. Rogers,
are worthy of all praise. The softeni