Mr, M. M. Piifctisoii Muir on Cheuiical Classljieation. 257 

 resistance of the bobbin must always be less than the external 

 resistance. Putting ^ for //,, we have 



8 + 2p 

 which expresses the physical law, namely that 



resistance of bobbin diameter of bare wire 



external resistance diameter of covered wire 



Alipore, Calcutta^ 

 July 31, 1877. 



XXXIV. On Chemical Classification. By M. M. Pattison 



Muir, F.R.S.E., Assistant Lecturer on Chemistry^ The 



Owens College J Manchester. 



[Concluded from p. 206.] 

 27. O far as actual experiments, taken in conjunction with 

 ^ the theory of valency and that of atom-linking, allow 

 us to judge, it would appear that there is a close connexion 

 between the valency of the atoms constituting a compound and 

 the general properties, chemical as well as physical, of that 

 compound, but that the position of the atom in the molecule 

 also influences the character of the molecule. On this view it 

 W' ill be possible to regard the properties of a compound as func- 

 tions (1) of the nature of the constituent atoms, and (2) of the 

 manner in which these atoms are linked together. By the 

 word ''nature," as here used, is to be understood all those 

 properties (atomic weight, density, valency, &c. &c.) which are 

 inherent in the atom considered as an individual existence. 



This view has much to recommend it, but as yet it can 

 only be regarded as a good working hypothesis ; adopting it 

 as such, lines of work may be marked out, along which the 

 researches of chemists may proceed for many years to come. 

 We shall first require careful researches into the " nature " of 

 the chemical atoms ; this is an immense field. We shall then 

 have another wide field for research in the circumstances 

 which condition the valency of the atoms. The connexion be- 

 tween physical properties and valency, and many other ques- 

 tions, will be included in these two main lines of research. 

 But while working in these directions in the past, and, I 

 doubt not, while working in these directions in the future, 

 chemists have ever and anon found the question. What is 

 chemical energy? what do we mean by chemical affinity? 



Phil Mag. S. 5. Vol. 4. No. 25. Oct. 1877. S 



