66 the president's address. 



objects than the gas for the sake of which the coal was originally- 

 distilled. 



The value of a by-product will naturally depend upon the 

 particular circumstances of the case, and what is useless, or 

 even harmful, under one set of conditions may be extremely 

 valuable under another. It may be a question of labour supply 

 or of transport, or it may be that the discovery of some new 

 process of manufacture in a totally different industry suddenly 

 creates a demand for a by-product that was previously almost or 

 entirely worthless. It is perhaps not too much to say that the 

 success or failure of a manufacturer in his business must in 

 many cases depend upon the ingenuity that he exhibits in 

 disposing of his by-products ; but the formation of such products 

 in the first instance cannot be avoided, and they may go on being 

 produced, and constitute a characteristic feature of the industry 

 for a long time, before some new factor in the circumstances of 

 the case may give them a special value of their own. It may 

 well be that this may never happen at all, and the substances 

 in question may simply accumulate in harmless, if unsightly, 

 heaps, or, on the other hand, they may become so offensive, 

 or even dangerous, as to render impossible the continuance of 

 the industry which gives rise to them. 



In short, it would be difficult to exaggerate the importance 

 of the part played by by-products in the evolution of human 

 industries. Such industries are necessarily subjected to a severe 

 struggle for existence in ceaseless competition with one another, 

 and in this struggle the by-products afford abundant opportunity 

 for the elimination of the least fit by the process of natural 

 selection. The by-products, however, did not themselves arise 

 through any process of selection, but as the unintentional and 

 inevitable results of those chemical and physical changes which 

 accompany the manufacture of the main product. 



We may thus look upon a human industry as an organism, 

 which undergoes a process of evolution subject to the control 

 of natural selection, and some of the most characteristic features 

 of which are to be found in its by-products. Indeed it may 

 often be recognised and identified by its by-products almost if 

 not quite as readily as by the product for the sake of which 

 it primarily exists. 



We must not, of course, push our analogy too far, but I hope to 



