506 Prof. L. Meyer on the 



throughout his whole life, and, moreover, impress others with 

 their truth for many years, was a consequence of the enormous 

 benefit which his systematic arrangement conferred on che- 

 mical science. Even his system died, as soon as its incom- 

 petence to classify organic compounds became manifest ; and 

 the chemical world looked on its departure with indifference. 



From this period, however, the speculations of chemists 

 ran in quite a new channel. It was not so necessary to 

 investigate the mode of action of the forces of affinity, as to 

 prepare and examine the wonderful forms of combination 

 which by its influence the atoms could be induced to assume 

 in organic compounds. This work for long absorbed the 

 attention of chemists. The obstinate battles fought over the 

 laws governing the linkage of atoms are still so fresh in the 

 minds of at least the older of the present generation of 

 chemists, that they need not here be more than mentioned. 



During this contest regarding the constitutional formulae 

 of organic compounds, a complete revolution of the doctrines 

 of affinity was in progress, which was prompted chiefly by 

 facts in inorganic Chemistry. Chemists had persistently clung 

 to the assumption, long before proved untenable, that heat 

 was a form of matter capable of entering into combination with 

 other forms of matter to produce chemical compounds. Al- 

 though Rum ford, at the end of last century, had proved that 

 heat is a mode of motion (a view held even in the 16th and 

 17th centuries*), and Davy had furnished a brilliant con- 

 firmation of his proof, yet even up to the middle of this century 

 it was stated in the most widely-read textbooks of Chemistry 

 that heat, light, and electricity are to be regarded as impon- 

 derable forms of matter. It must be noted that, though 

 rejected by all journals of Physics, Julius Robert Mayer's 

 treatise received compensation, oddly enough, by finding 

 a resting-place in Liebig's ' Annals of Chemistry' f. With 

 the recognition of the importance of the mechanical theory 

 of heat arose the hope that, by its help, our knowledge of the 

 doctrine of affinity might be materially advanced. 



The view was at once suggested that, just as a heavy body, 

 in consequence of the mutual attraction between it and the 

 earth, moves towards the earth with accelerated velocity, 

 thereby converting potential energy, due to its elevated 

 position, into kinetic energy, so the atoms, as a consequence 

 of their affinity, move towards each other, converting their 

 affinity into energy of motion, which, as a rule, is manifested 

 in the form of heat. According to this doctrine, the heat 



* Bacon, Novum Organum, Lib. ii. Aph. xx. 

 f Ann. Chem. Pharm, 1842, vol. xlii. p, 233. 



