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of experimental science , the advances of the human mind have been very gradual : Mayow , in 1674 , was upon the very brink of that stream of
discovery , which , in 1774 , carried Dr . Priestley into the fastnesses of Pneumatic Chemistry . Hales , by shewing the raode of disengaging and collecting gaseous fluids , removed many of the most serious obstacles which
encumbered this path of research ; he was followed by Boerhaave , and afterwards by Black , who , having reached the discovery of fixed air , turned into another road of investigation .
Neither Mayow , therefore , nor Hales , nor Boerhaave , nor Black , were very diligent cultivators of Pneumatic Chemistry : they had , indeed ,, opened the mine , but did not explore it 5 its treasures were reserved for those Whose
labours we are now about to recount , and were chiefly borne away by the diligent dexterity of Dr . Joseph Priestley , If we trust the quotations of Rey already cited , the necessity of air , in the process of combustion , was not
only observed , but inquired into by Csesalpinus * and L . ibavius , f as far back as the sixteenth and early part of the seventeenth century . Mayow insisted that a part only of the atmosphere was concerned in the phenomena of combustion , and found that air in which bodies had burned
became unfit for the respiration of animals * As soon as it had been ascertained that , in the phenomena of combustion and respiration , a portion of fixed air was generated , the extinction of burning bodies , and the death of animals immersed in air , thus rendered foul , were referred to the presence of that gaseous body , its noxious qualities having been amply
* Bom at Arczzo in 1519 5 died at Rome in 1603 . His medical works contain some scattered chemical observations winch , however , are of little importance . f Libavius has sometimes been cited as the most rational chemical inquirer of his ag-e , but of this character 1 can find no justification in his writings upon chemical subjects 5 they arc either unintelligible or trifling- ; ! i « certainly had some merit as a contriver of apparatus , and his furnaces and distillatory vessels appear to have been ingeniously devised . He died in 1616 .
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proved by Black and others ; and this opinion seemed to be sanctioned by the discovery , that air thus tainted by respiration and combustion , might , in some measure , be restored to purity by exposure to the action of lime water , which absorbed the fixed air .
In 1772 , Dr . Rutherford , Professor of Botany in the University of Edinburgh , published a thesis on fixed , or , as it was then called , niepliirie air , from which the following passage is extracted : " By the respiration of animals , healthy air is not merely
rendered mephitic , but also suffers another change . For , after the mephitic portion is absorbed by a caustic alcaline lixivium , the remaining portion is not rendered salubrious , and although it occasions no precipitate in lime water , it nevertheless extinguishes flame , and destroys life . "
Thus we have traced the discovery of two gaseous fluids differing from common air : fixed air , discovered by Black , and azote , as it has since been called , by Rutherford- The former ,
a component part of chalk , and of the mild alcalis , the product of the combustion of charcoal , and of the respiration of animals 3 the latter an ingredient of atmospheric air .
Jt would be a wearisome and unprofitable occupation to record , even in brief terms , the transactions of a set of cavilling philosophists who started up in this country , and elsewhere , about the present period of our history 5 their names have sunk into oblivion , and their works were
only read while recommended by novelty . Some of them I have reluctantly perused , and have found that they are rather calculated to weary the attention than to satisfy curiosity , or impart information . I , therefore , hasten to one of the
most remarkable and splendid epochs of chemical science , adorned by discoveries which have been rarely equalled , either in number or importance , and ushered in by a series of sterling facts and memorable
investigations . The well-known names of Priestley , Scheele , Cavendish and L . avoisier , now appear upon the stage , and it will be an arduous but gratifying task to follow them through their respective parts . In this recital , a strict adherence to the dates of discoveries would neither be convenient
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676 Mr * Brande ' s Estimate of Dr . Priestley s Chemical Discoveries .
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Citation
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Monthly Repository (1806-1838) and Unitarian Chronicle (1832-1833), Nov. 2, 1818, page 676, in the Nineteenth-Century Serials Edition (2008; 2018) ncse.ac.uk/periodicals/mruc/issues/vm2-ncseproduct2482/page/12/
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