ANIONS, CATIONS, AND ELECTRO-CHEMICAL EQUIVALENTS. 



115 



Cations. 



Hydrogen 1 



Potassium 39-2 



Sodium 23-3 



Lithium 10 



Barium 68-7 



Strontium 43-8 



Calcium 20-5 



Magnesium 12' 7 



Manganese 27*7 



Zinc 32-5 



Tin 57-9 



Lead 103-5 



Iron 28 



Copper 31-6 



Cadmium 55*8 



Cerium 46 



Cobalt 29-5 



Nickel 29-5 



Antimony 64-6? 



Bismuth 71 



Mercury 200 



Silver 108 



Platina 98-6? 



Gold (?) 



Ammonia 17 



Potassa 47*2 



Soda 31-3 



Lithia 18 



Baryta 76*7 



Strontia 51'8 



Lime 28-5 



Magnesia 20*7 



Alumina (?) 



Protoxides generally. 



Quinia 171-6 



Cinchona 1 60 



Morphia 290 



Vegeto-alkalies generally. 



848. This Table might be further arranged into groups of such substances as either 

 act with, or replace, each other. Thus, for instance, acids and bases act in relation 

 to each other; but they do not act in association with oxygen, hydrogen, or ele- 

 mentary substances. There is indeed little or no doubt that, when the electrical 

 relations of the particles of matter come to be closely examined, this division must be 

 made. The simple substances, with cyanogen, sulpho-cyanogen, and one or two 

 other compound bodies, will probably form the first group ; and the acids and bases, 

 with such analogous compounds as may prove to be ions, the second group. Whe- 

 ther these will include all ions, or whether a third class of more complicated results 

 will be required, must be decided by future experiments, 



849. It is probable that all our present elementary bodies are ions, but that is not 

 as yet certain. There are some, such as carbon, phosphorus, nitrogen, silicon, boron, 

 alumium, the right of which to the title of ion it is desirable to decide as soon as 

 possible. There are also many compound bodies, and amongst them alumina and 

 silica, which it is desirable to class immediately by unexceptionable experiments. 

 It is Rho possible, that all combinable bodies, compound as well as simple, may enter 

 into the class of ions ; but at present it does not seem to me probable. Still the expe- 

 rimental evidence I have is so small in proportion to what must gradually accumulate 

 around, and bear upon, this point, that I am afraid to give a strong opinion upon it. 



850. I think I cannot deceive myself in considering the doctrine of definite electro- 

 chemical action as of the utmost importance. It touches by its facts more directly 

 and closely than any former fact, or set of facts, have done, upon the beautiful idea, 

 that ordinary chemical affinity is a mere consequence of the electrical attractions of 

 the particles of different kinds of matter ; and it will probably lead us to the means by 

 which we may enlighten that which is at present so obscure, and either fully demon- 

 strate the truth of the idea, or develope that which ought to replace it. 



851. A very valuable use of electro-chemical equivalents will be to decide, in cases 

 of doubt, what is the true chemical equivalent, or definite proportional, or atomic 

 number of a body ; for I have such conviction that the power which gt>verns electro- 

 decomposition and ordinary chemical attractions is the same ; and such confidence in 

 the overruhng influence of those natural laws which render the former definite, as to 



q2 



