lire's Dictionary of Chemist ly. 345 



received Rimost universal adoption, though not till after considerable hesi- 

 tation and opposition; and it nas made a complete revolution in chemical 

 science.' The French theory of chemistry, as it was called, or hypothesis of 

 combustion as it should have been named, was for some time classed in cer- 

 tainty with the theory of gravitation. Alas! it has vanished with the lu- 

 minous phantoms of the day ; but the sound logic, the pure candour, the 

 numerical precision of inference, which characterize Lavoisier's elements, 

 will cause his name to be held in everlasting admiration. 



" It was the rival logic of Sir H. Davy, aided by his unrivalled felicity 

 of investigation, which first recalled chemistry from the pleasing labyrinths 

 of fancy, to the more arduous butfar more profitable and progressive career 

 of reason. His researches on combustion and flame, already rich in bless- 

 ings to mankind, would alone place him in the first rank of scientific genius. 

 I shall give a pretty copious account of them, since by some fatality it has 

 happened, that in o«r best and largest system, where so many pages are 

 devoted to the reveries of ancient chemists, the splendid and useful truths 

 made known by the great chemist of England have been totally overlooked. 



*' Whenever the chemical forces which determine either combination or 

 decomposition are energetically exercised, the phenomena of combustion, 

 or incandescence with a change of properties, are displayed. The distinc- 

 tion, therefore, between supporters of combustion and combustibles, on 

 which some late systems are arranged, is frivolous and partial. In fact, 

 one substance frequently acts in both capacities, being a supporter ap- 

 parently at one time, and a combustible at another. But in both cases the 

 heat and light depend on the same cause, and merely indicate the energy 

 and rapidity with which reciprocal attractions are exerted. 



" Thus, sulphuretted hydrogen is a combustible with oxygen and chlo- 

 rine ; a supporter with potassium. Sulphur, with chlorine and oxygen, 

 has been called a combustible basis ; with metals it acts the part of a sup- 

 porter ; for incandescence and reciprocal saturation result. In like manner, 

 potassium unites so powerfully with arsenic and tellurium as to produce 

 the phenomena of combustion. Nor can we ascribe the phenomena to ex- 

 trusion of latent heat, in consequence of condensation of volume. The 

 protoxide of chlorine, a body destitute of any combustible constituent, at 

 the instant of decomposition, evolves light and heat with explosive violence ; 

 and its volume becomes one-fifth greater. Chloride and iodide of azote, 

 compounds alike destitute of any inflammable matter, according to the 

 ordinary creed, are resolved into their respective elements with tremendous 

 force of inflammation ; and the first expands into more than 600 times its 

 bulk. Now, by tlie prevailing hypothesis of latent heat, instead of heat 

 and light, a prodigious cold ought to accompany such an expansion. The 

 chlorates and nitrates, in like manner, treated with charcoal, sulphur, 

 phosphorus, or metals, deflagrate or detonate, while the volume of the com- 

 bining substances is greatly enlarged. The same thing may be said of the 

 nitrogurets of gold and silver. In truth, the combustion of gunpowder, a 

 phenomenon too familiar to mankind, should have been a bar to the recep- 

 tion of Lavoisier's hypothesis of combustion. The subterfuges which have 

 been adopted, and admitted, in order to reconcile them, are unworthy to 

 be detailed. 



" From the preceding facts, it is evident, 1st, That combustion is not 

 necessarily dependent on the agency of oxygen ; 2d, That the evolution of 

 the heat, is not to be ascribed simply to a gas parting with its latent store 

 of that ethereal fluid, on its fixation, or combustion ; and, 3dly, That ' no 



Eeculiar substance or form of matter is neceissary for producing the eftect, 

 ut that it is a general result of the actions of any substances possessed of 

 strong' chemical attractions, or different electrical relations, and that it 

 takes place in all cases in which an intense and violent motion, can be 

 conceived to be communicated to the corpuscles of bodies.' 



" All chemical phenomena indeed may he justly ascribed to motions 

 among the ultimate particles of matter, tending to change the constitution 

 of the mass. 



" It was fashionable for awhile, to attribute the ciloric evolved in com- 

 bustion, to a diminished capcity for heat of the resulting substance. 

 Some phenomena, inaccurately observed, gave rise to this generalization. 

 On this subject 1 shall content myself with stating the condunions to which 

 MM. DttJong and Petit hav» come, in consequence of ilu if owu recent re- 



