M^ 



iNDtrcrrioN. 



not laws of causation, but there is no 

 reason to believe that they depend on 

 any common cause ; all appearances 

 are in favour of their depending on 

 the particular collocation of natural 

 agents which at some time or other 

 existed on our globe, and from which 

 no inference can be drawn as to the 

 collocation which exists or has existed 

 in any other portion of the vmi verse. 



§ 6. Our definition of an empirical 

 law including not only those uni- 

 formities which are not known to 

 be laws of causation, but also those 

 which are, provided there be reason 

 to presume that they are not ultimate 

 laws, this is the proper place to con- 

 sider by what signs we may judge 

 that even if an observed uniformity 

 be a law of causation, it is not an 

 ultimate but a derivative law. 



The first sign is, if between the 

 antecedent a and the consequent b 

 there be evidence of some intermedi- 

 ate link, some phenomenon of which 

 we can surmise the existence, though 

 from the imperfection of our senses 

 or of our instruments we are unable 

 to ascertain its precise nature and 

 laws. If there be such a phenomenon, 

 (which may be denoted by the letter 

 X,) it follows that even if a be the 

 cause of 6, it is but the remote cause, 

 and that the law, a causes h, is re- 

 solvable into at least two laws, a 

 causes x, and x causes h. This is a 

 very frequent case, since the opera- 

 tions of nature mostly take place on 

 so minute a scale, that many of the 

 successive steps are either impercep- 

 tible, or very indistinctly perceived. 



Take, for e.\ ample, the laws of the 

 chemical composition of substances, 

 as that hydrogen and oxygen being 

 combined, water is produced. All 

 we see of the process is, that the two 

 gases being mixed in certain propor- 

 tions, and heat or electricity being 

 applied, an explosion takes place, the 

 gases disappear, and water remain*. 

 There is no doubt about the law, or 

 about its being a law of causation. 

 But between the antecedent (the 



gases in a state of mechanical mix- 

 ture, heated or electrified) and the 

 consequent (the production of water) 

 there must be an intermediate pro- 

 cess which we do not see. For if we 

 take any portion whatever of the 

 water and subject it to analysis, we 

 find that it always contains hydro- 

 gen and oxygen ; nay, the very same 

 proportions of them, namely, two- 

 thirds in volume of hydrogen, and 

 one-third oxygen. This is true of a 

 single drop ; it is true of the minutest 

 portion which our instruments are 

 capable of appreciating. Since, then, 

 the smallest perceptible portion of 

 the water contains both these sub- 

 stances, portions of hydrogen and 

 oxygen smaller than the smallest 

 perceptible must have come together 

 in every such minute portion of 

 space ; must have come closer to- 

 gether than when the gases were in 

 a state of mechanical mixture, since 

 (to mention no other reasons) the 

 water occupies far less space than 

 the gases. Now, as we cannot see 

 this contact or close approach of the 

 minute particles, we cannot observe 

 with what circumstances it is at- 

 tended, or according to what laws it 

 produces its effects. The production 

 of water, that is, of the sensible 

 phenomena which characterise the 

 compound, may be a very remote 

 effect of those laws. There may be 

 innumerable intervening links ; and 

 we are sure that there must be some. 

 Having full proof that corpuscular 

 action of some kind takes place pre- 

 vious to any of the great transforma- 

 tions in the sensible properties of sub- 

 stances, we can have no doubt that 

 the laws of chemical action, as at 

 present known, are not ultimate but 

 derivative laws ; however ignorant 

 we may be, and even though we 

 should for ever remain ignorant, of 

 the nature of the laws of corpuscular 

 action from which they are derived. 



In like manner, all the processei 

 of vegetative life, whether in the 

 vegetable properly so called or in the 

 animal body, are corpuscular pro- 



