﻿M. Dumas's Remarks on Affinity. 83 



reflections on chemical phenomena, showing by the accuracy of 

 his details and the depth of his views that the humble practical 

 investigations of the laboratory were as familiar to him as the 

 most elevated conceptions of celestial mechanics*: — 



" Have not the small particles of bodies certain powers, virtues 

 or forces by which they act at a distance not only upon the rays of 

 light for reflecting, refracting, and inflecting them, but also upon 

 one another for producing a great part of the phenomena of 

 nature ? For it is well known that bodies act upon one another 

 by the attractions of gravity, magnetism, and electricity; and. 

 these instances show the tenour and course of nature, and make 

 it not improbable but that there may be more attractive powers 

 than these. For Nature is very consonant and conformable to 

 herself. How these attractions may be performed I do not here 

 consider. 



"What I call attraction may be performed by impulse, or by 

 some other means unknown to me. I use that word here to 

 signify in general any force by which bodies tend towards one 

 another, whatsoever be the cause. For we must learn from the 

 phenomena of Nature what bodies attract one another and what 

 are the laws and properties of the attraction, before we inquire 

 the cause by which the attraction is performed. 



"The attractions of gravity, magnetism, and electricity reach 

 to very sensible distances, and so have been observed by vulgar 

 eyes; and there may be others w r hicb reach to so small distances 

 as hitherto escaped observation ; and perhaps electrical attrac- 

 tion may reach to such small distances even without being ex- 

 cited by friction." 



Newton explains by this attraction the property which certain 

 salts possess of absorbing water from the air, and the difficulty of 

 separating this water from them by heat ; he also thus explains the 

 absorption of aqueous vapour by sulphuric acid, and the heat 

 developed by mixing this acid with water : — 



"When spirit of vitriol poured upon common salt or saltpetre 

 makes an ebullition with the salt and unites with it, and in dis- 

 tillation the spirit of the common salt or saltpetre comes over 

 much easier than it would do before, and the acid part of the 

 vitriol stays behind, does not this argue that the fixed alkali of 

 the salt attracts the acid spirit of the vitriol more strongly than 

 its own spirit, and not being able to hold them both, lets go 

 its own ? 



* [As M. Dumas does not mention whence he has taken Newton's 

 statements, the passages in the text are taken from the ' Optics,' Book III. 

 (vol. iv. p. 242 et seq. of Horsley's edition of Newton). In some cases M. 

 Dumas appears to have summed up in his own language Newton's views. 

 Where it could be done without undue length the corresponding original 

 passage has been given. — Eds.] 



G2 



