42 INDUCTION, 



permeate animal membranes : that opium and alcohol 

 intoxicate : that substances containing a very high 

 proportion of nitrogen (such as hydrocyanic acid and 

 morphia) are powerful poisons : that when different 

 metals are fused together the alloy is harder than the 

 various elements : that the number of 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, 

 presumed to be resolvable into simpler laws, but not 

 yet resolved into them. The ascertainment of the 

 empirical laws of phenomena, often precedes by a 

 long interval the explanation of those laws by the 

 Deductive Method : and the verification of a deduc- 

 tion usually consists in the comparison of its results 

 with empirical laws previously ascertained. 



2. From a limited number of ultimate laws of 

 causation, there are necessarily generated a vast 

 number of derivative uniformities, both of succession 



* 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 carbon- 

 ates, &c. Again, bodies largely composed of combustible ele- 

 ments, 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 processes of inquiry, 

 leading to the discovery of these laws. 



