TRAINS OF REASONING. 235 



poisonous, the substance which is before me is arsenic, 

 therefore it is poisonous. The truth of the minor may not 

 here be obvious at first sight; it may not be intuitively evi- 

 dent, but may itself be known only by inference. It may be 

 the conclusion of another argument, which, thrown into the 

 syllogistic form, would stand thus : Whatever when lighted 

 produces a dark spot on a piece of white porcelain held in the 

 flame, which spot is soluble in hypochlorite of calcium, is 

 arsenic ; the substance before me conforms to this condition ; 

 therefore it is arsenic. To establish, therefore, the ultimate 

 conclusion, The substance before me is poisonous, requires a 

 process, which, in order to be syllogistically expressed, stands 

 in need of two syllogisms ; and we have a Train of Reasoning. 

 When, however, we thus add syllogism to syllogism, we 

 are really adding induction to induction. Two separate 

 inductions must have taken place to render this chain of 

 inference possible ; inductions founded, probably, on different 

 sets of individual instances, but which converge in their 

 results, so that the instance which is the subject of inquiry 

 comes within the range of them both. The record of these 

 inductions is contained in the majors of the two syllogisms. 

 First, we, or others for us, have examined various objects 

 which yielded under the given circumstances a dark spot with 

 the given property, and found that they possessed the proper- 

 ties connoted by the word arsenic; they were metallic, volatile, 

 their vapour had a smell of garlic, and so forth. Next, we, or 

 others for us, have examined various specimens which pos- 

 sessed this metallic and volatile character, whose vapour had 

 this smell, &c., and have invariably found that they were 

 poisonous. The first observation we judge that we may ex- 

 tend to all substances whatever which yield that particular 

 kind of dark spot ; the second, to all metallic and volatile sub- 

 stances resembling those we examined ; and consequently, not 

 to those only which are seen to be such, but to those which 

 are concluded to be such by the prior induction. The sub- 

 stance before us is only seen to come within one of these 

 inductions ; but by means of this one, it is brought within the 

 other. We are still, as before, concluding from particulars to 



