214 INDUCTION. 



has yet been made in bringing the special laws under general ones 

 from which they may be deduced ; but there are even in chemistry 

 many circumstances to encourage the hope that such general laws 

 will hereafter be discovered. The different actions, of a chemical 

 compound will never, undoubtedly, be found to be the sum of the 

 actions of its separate elements; but there may exist, between the 

 properties of the compound and those of its elements, some constant 

 relation, which if discoverable by a sufficient induction, would enable 

 us to foresee the sort of compound which will result from a new com- 

 bination before we have actually tried it, and.to jiulge of what sort of 

 elements some new substance is- compounded before we have analyzed 

 it : a problem, • the solution of which has been propounded by M. 

 Comte as the ideal aim and purpose of chemical speculation. The 

 gi-eat law of definite proportions, first discovered in its full generality 

 by Dalton, is a complete solution of this problem in one single aspect 

 (of secondary importance it is ti-ue), that of quantity : and in respect 

 to quality, we have already some partial generalizations sufficient to 

 indicate "the possibility of ultimately proceeding further. We can 

 predicate many common properties of the kind of compounds which 

 result from the combination, in each of the small number of possible 

 proportions, of any acid whatever with any base. We have also the 

 very curious law, discovered by Berthollet, that two soluble salts 

 mutually decompose one another whenever the new combinations 

 w^hich result produce an insoluble compound : or one less soluble 

 than the two former. Another imifonnity has been obsei-v^ed, com- 

 monly called the law of isomorphism ; the identity of the crystalline 

 forms of substances which possess in common certain peculiarities of 

 chemical composition. Thus' it appears that even heteropathic laws, 

 such laws of combined 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 principle. There may, therefore, be laws 

 of the o-eneration of laws from others dissimilar to them; and in chem- 

 istry, these undiscovered laws of the dependence of the properties of 

 the compound on the properties of its elements, may, together with 

 the laws of the elements themselves, furnish the premisses by which 

 the science is 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 

 actino- singly : but that this rule, though genei'al, is not universal ; that 

 in some instances, at some particular points in the transition fi'om sep- 

 arate to united action, the laws change, and an entirely new set of 

 effects are either added to, or take the place of, those which arise fi'om 

 the separate agency of the same causes ; the Ia\vs of these new effects 

 being again susceptible of composition, 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, although it is encumbered with many difficulties and apparent 

 exceptions, which much ingenuity has been expended in showing not 

 to be real ones. This proposition, in so far as it is brue, enters as a 



