DISCOVERIES IN THE CELESTIAL SPACES. 343 



in 1553, had noticed the increase of weight that accompanies 

 the oxydation of lead, and, perfectly in accordance with the 

 idea of the myth of Phlogiston, had attributed it to the escape 

 of a " celestial fiery matter," causing levity ; and it was not 

 until eighty years afterward that Jean Rey, a remarkably 

 skillful experimenter at Bergerac, who had investigated with 

 the greatest care the increase of weight during the calcination 

 of lead, tin, and antimony, arrived at the important conclu- 

 sion that this increase of weight must be ascribed to the ac- 

 cess of the air to the metallic calx. " Je responds et soutiens 

 glorieusement," he says, " que ce surcroit de poids vient de 

 Fair qui dans le vase a ete espessi."* 



Men had now discovered the path which was to lead them 

 to the chemistry of the present day, and through it to the 

 knowledge of a great cosmical phenomenon, viz., the connec- 

 tion between the oxygen of the atmosphere and vegetable life. 

 The combination of ideas, however, which presented itself to 

 the minds of distinguished men, was strangely complicated in 

 its nature. Toward the close of the seventeenth century a 

 belief arose in the existence of nitrous particles {spiritus nitro- 

 dereus pabulum nitrosicni), which, contained in the air, and 

 identical with those which are fixed in saltpetre, were sup- 

 posed to possess the necessary requirements for combustion ; 

 an opinion which, obscurely expressed by Hooke in his Micro- 

 graphia (1671), is found more fully developed by Mayow in 

 1669, and by Willis in 1671. " It was maintained that the 

 extinction of flame in a closed space is not owing to the over- 

 saturation of the air with vapors emanating from the burning 

 body, but is the consequence of the entire absorption of the 

 spiritus nitro-ah'eus contained in the nitrogenous air." The 

 sudden increase of the glowing heat when fusing saltpetre • 

 (emitting oxygen) is strewed upon coals, and the formation of 



* Rey, strictly speaking, only mentions the access of air to the oxyds; 

 he did not know that the oxyds themselves (which were then called 

 the earthy metals) are only combinations of metals and air. Accord- 

 ing to him, the air makes " the metallic calx heavier, as sand increases 

 in weight when water hangs about it." The calx is susceptible of be- 

 ing saturated with air. " L'air espaissi s'attache a la chaux, ainsi le 

 poids augmente du commencement jusqu'd la fin: mais quand tout en , 

 est afi'uble, elle n'en S(jauroit prendre d'avantage. Ne continuez plus 

 votre calcination soubs cet espoir, vous perdriez vostre peine." Key's 

 work thus contains the first approach to the better explanation of a 

 phenomenon, whose more complete understanding subsequently exer- 

 cised a favorable influence in reforming the whole of chemistry. See 

 Kopp, Gesch. der Chemie, th. iii., s. 131-133. (Compare, also, in the same 

 work, th. i., s. 116-127, and th. iii., s. 119-138, as well as s. 175-195.) 



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