EMPIRICAL LAWS. 39 



atoms of acid required to neutralize one atom of any base, 

 is equal to the number of atoms of oxygen in the base : 

 that the solubility of substances in one another, depends* 

 (at least in some degree) on the similarity of their elements. 



An empirical law, then, is an observed uniformity, pre- 

 sumed to be resolvable into simpler laws, but not yet resolved 

 into them. The ascertainment of the empirical laws of pheno- 

 mena often precedes by a long interval the explanation of 

 those laws by the Deductive Method; and the verification of 

 a deduction usually consists in the comparison of its results 

 with empirical laws previously ascertained. 



2. From a limited number of ultimate laws of causa- 

 tion, there are necessarily generated a vast number of deriva- 

 tive uniformities, both of succession and of coexistence. 

 Some are laws of succession or of coexistence between 

 different effects of the same cause : of these we had ex- 

 amples in the last chapter. Some are laws of succession' 

 between effects and their remote causes ; resolvable into the 

 laws which connect each with the intermediate link. Thirdly, 

 when causes act together and compound their effects, the 

 laws of those causes generate the fundamental law of the 

 effect, namely, that it depends on the coexistence of those 

 causes. And, finally, the order of succession or of co- 

 existence which obtains among effects, necessarily depends 

 on their causes. If they are effects of the same cause, it 

 depends on the laws of that cause ; if on different causes, it 

 depends on the laws of those causes severally, and on the 

 circumstances which determine their coexistence. If we 



* Thus, water, of which eight-ninths in weight are oxygen, dissolves most 

 bodies which contain a high proportion of oxygen, such as all the nitrates, 

 (which have more oxygen than any others of the common salts,) most of the 

 sulphates, many of the carbonates, &c. Again, bodies largely composed of 

 combustible elements, like hydrogen and carbon, are soluble in bodies of similar 

 composition ; rosin, for instance, will dissolve in alcohol, tar in oil of turpentine. 

 This empirical generalization is far from being universally true ; no doubt 

 because it is a remote, and therefore easily defeated, result of general laws too 

 deep for us at present to penetrate ; but it will probably in time suggest pro- 

 cesses of inquiry, leading to the discovery of those laws. 



