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Rh chosen field was natural history, and before he was nineteen, at which age he published his first scientific paper on conchology, he had made extensive collections. In his search for specimens at the bottom of the sea, he pushed out into deep water and claimed to be the first to enter upon the work of deep-sea dredging. He studied with Agassiz, and in 1852 accompanied him to Norfolk to investigate the marine fauna of that region. He was appointed naturalist to the North-Pacific Exploring Expedition, and spent three and a half years (1852-1856) in observations and collections. For nine years after his return, he remained for the most part in the Smithsonian Institution, working up the results of his worldwide explorations. He became curator of the Chicago Academy of Sciences in 1864, and was soon after elected secretary.

In an able obituary address before the Chicago Academy, President Foster has enumerated his chief contributions to science, and thus speaks of his labors in the institution:

He maintained a correspondence with not less than fourteen kindred societies at home and over one hundred abroad. He organized a system of exchanges by which our library was supplied with the scientific journals and Transactions, and our museum enriched with natural-history specimens from every quarter of the globe: He edited, with an accuracy of proof-reading rarely surpassed, the two parts of our Transactions, and prepared our annual reports with an almost commercial exactness. So thoroughly classified were the collections, that he could instantly refer the scientific inquirer to the particular specimen required. Under his directorship, the collections in certain departments of natural history had grown to be the most complete in the country; and learned foreigners, in pursuit of information, resorted here as to one of the chosen seats of science. This vast collection had been accumulated within the short space of five years; for, on the 7th of June, 1866, our previous accumulations were almost wholly destroyed by fire. Under this calamity Stimpson bore up manfully, but when the tremendous catastrophe of the 8th of October occurred he was, as it were, crushed to earth. From that time, I think, his spirit lost its buoyancy; and, while he assumed an air of cheerfulness, in his quivering lip and tremulous voice it was easy to detect what he would fain conceal. The iron had entered his soul. Let him who would accuse our friend of undue weakness, read over the melancholy catalogue of losses prepared by the secretary, and dated the 30th of October last, and then call to mind that, in addition to the total destruction of the Academy's collections, which he had arranged and classified, his own collections had been involved in the general calamity; rare books, obtained with difficulty, or presentation copies bearing the autographs of the authors; shells which he had dredged from the ocean all the way from Nova Scotia to the Japanese Sea; and manuscripts in which were embodied the results of twenty years of almost unremitting scientific labor, and whose publication he fondly hoped would form the solid basis of his fame.

Dr. Stimpson had long suffered from weakness of the lungs, and died of hemorrhage May 26, 1872, aged 41.

Purification of Coal-Gas.—In the ordinary process of manufacturing coal-gas it is found necessary to put the product through a course of purification before it is fit for illuminating purposes. The sulphur compounds are the most deleterious of its impurities, and how these may be best removed forms the subject of an instructive lecture, recently delivered by Mr. Vernon Harcourt at the Royal Institution, from which we condense the following: Sulphur being an almost constant constituent of the coal from which gas is made, it is volatilized in the retorts and passes over with the gas in combination with its two principal elements, carbon and hydrogen. Unpurified coal-gas thus contains sulphuretted hydrogen—the gas of rotten eggs—and bisulphide of carbon. A considerable part of the sulphuretted hydrogen is removed in the "condensers" and "scrubbers" by the action of water and ammonia. It has, however, been found that, if coal-gas is washed too much, its illuminating power is greatly impaired, and indeed all washing does some injury to it in this respect. To complete the removal of sulphuretted hydrogen, the washed coal-gas is passed through large boxes, containing either lime or oxide of iron, and which are termed purifiers. Either of these substances acts very effectually in depriving coal-gas of its sulphuretted hydrogen. Lime is the cheaper material, but has the serious drawback that when saturated with sulphuretted hydrogen its smell is very offensive, so that when taken out of the purifiers it becomes