“We shall try the gases in every possible way. They may be condensed by pressure and rarefied by heat. _Quere_,--Would not a powerful injecting syringe furnished with two valves, one opening into an air-holder and the other into the breathing chamber, answer the purpose of compression better than any other apparatus? Can you not, from your extensive stores of philosophy, furnish us with some hints on this subject? May not the non-respirable gases furnish a class of different stimuli? of which the oxymuriatic acid gas [chlorine] would stand the highest, if we may judge from its effects on the lungs; then, probably, _gaseous oxyd of azote_ [nitrous oxide?] and _hydrocarbonate_ [the gases obtained by passing steam over red-hot charcoal]. “I suppose you have not heard of the discovery of the native _sulphate of strontian_ in England. I shall perhaps surprise you by stating that we have it in large quantities here. It had long been mistaken for _sulphate of barytes_, till our friend Clayfield, on endeavouring to procure the _muriate of barytes_ from it by decomposition, detected the strontian. We opened a fine vein of it about a fortnight ago at the Old Passage near the mouth of the Severn.[B]... “We are printing in Bristol the first volume of the ‘West Country Collection,’ which will, I suppose, be out in the beginning of January. “Mrs. Beddoes ... is as good, amiable, and elegant as when you saw her. “Believe me, dear Sir, with affection and respect, truly yours, “HUMPHRY DAVY.” [B] _Cf._ An account of several veins of Sulphate of Strontites, found in the neighbourhood of Bristol, with an Analysis of the different varieties. By W. Clayfield. “Nicholson’s Journ.,” III., 1800, pp. 36-41. The work alluded to in this letter made its appearance in the early part of 1799, under the title of “Contributions to Physical and Medical Knowledge, principally from the West of England; collected by Thomas Beddoes, M.D.” The first half of the volume, in accordance with the editor’s promise, is occupied by two essays from Davy: the first “On Heat, Light, and the Combinations of Light, with a new Theory of Respiration”; the second “On the Generation of Phosoxygen (Oxygen Gas), and on the Causes of the Colours of Organic Beings.”