246 



INDUCTION. 



tions, sufficient to Indicate the possi- 

 bility of ultimately proceeding farther. 

 We can predicate some common proper- 

 ties of the kind of compounds which re- 

 sult from the combination in each of the 

 small numberof possible proportions, of 

 any acid whatever with any base. We 

 have also the curious law, discovered 

 by Berthollet, that two soluble salts 

 mutually decompose one another when- 

 ever the new combinations which re- 

 sult produce an insoluble compound, 

 or one less soluble than the two for- 

 mer. Another uniformity is that 

 called the law of isomorphism ; the 

 identity of the crystalline forms of 

 substances which possess in common 

 certain peculiarities of chemical com- 

 position.* Thus it appears that even 

 heteropathic laws, such laws of com- 

 bined agency as are not compounded 

 of the laws of the separate agencies, 

 are yet, at least in some cases, derived 

 from them according to a fixed prin- 

 ciple. There may, therefore, be laws 

 of the generation of laws from others 

 dissimilar to them ; and in chemistry, 

 these undiscovered laws of the depend- 

 ence of the properties of the compound 

 on the properties of its elements, may, 

 together with the laws of the elements 

 themselves, furnish the premises b}' 

 which the science is perhaps destined 

 one day to be rendered deductive. 



It would seem, therefore, that there 

 is no class of phenomena in which 

 the Composition of Causes does not 

 obtain: that, as a general rule, causes in 

 combination produce exactly the same 

 effects as when acting singly ; but 

 that this rule, though general, is not 

 universal : that in some instances, at 

 some particular points in the transi- 

 tion from separate to united action, 

 the laws change, and an entirely new 

 set of effects are either added to, or 



* Professor Bain adds several other well- 

 established chemical generalisations : " The 

 laws that simple substances exhibit the 

 strongest affinities ; that compounds are 

 more fusible than their elements ; that 

 combination tends to a lower state of mat- 

 ter from gas down to solid ; " and aome 

 general propositions concerning the cir- 

 cumstances which facilitate or resist che- 

 mical combination {Logic, ii. 254). 



take the place of, those which arise 

 from the separate agency of the same 

 causes : the laws of these new effects 

 being again susceptible of composi- 

 tion to an indefinite extent, like the 

 laws which they superseded. 



§ 3. That effects are proportional 

 to their causes is laid down by some 

 writers as an axiom in the theory of 

 causation ; and great use is sometimes 

 made of this principle in reasonings 

 respecting the laws of nature, though 

 it is encumbered with many diffi- 

 culties and apparent exceptions, which 

 much ingenuity has been expended in 

 showing not to be real ones. This 

 proposition, in so far as it is true, 

 enters as a particular case into the 

 general principle of the Composition 

 of Causes ; the causes compounded 

 being, in this instance, homogeneous; 

 in which case, if in any, their joint 

 effect might be expected to be identi- 

 cal with the sum of their separate 

 effects. If a force equal to one 

 hundredweight will raise a certain 

 body along an inclined plane, a force 

 equal to two hundredweight will raise 

 two bodies exactly similar, and thus 

 the effect is proportional to the cause. 

 But does not a force equal to two 

 hundredweight actually contain in 

 itself two forces each equal to one 

 hundredweight, which, if employed 

 apart, would separately raise the two 

 bodies in question ? The fact, there- 

 fore, that when exerted jointly they 

 raise both bodies at once, results from 

 the Composition of Causes, and is a 

 mere instance of the general fact that 

 mechanical forces are subject to the 

 law of Composition. And so in every 

 other case which can be supposed. 

 For the doctrine of the proportionality 

 of effects to their causes cannot of 

 course be applicable to cases in which 

 the augmentation of the cause alters 

 the kind of effect ; that is, in which 

 the surplus quantity superadded to the 

 cause does not become compounded 

 with it, but the two together generate 

 an altogether new phenomenon. Sup- 

 pose that the application of a certain 



