BBITISH ASSOCIATION FOE THE ADVANCEMENT OF SCIENCE. 51 



Beginning then with Chemistry, as the subject with which I am most familiar, 

 let me remind you, that at a period not much more remote than the one alluded 

 to, all of it that could be quoted as really worthy the name of a science was com- 

 prehended within the limits of the mineral kingdom. Here at least the outline had 

 been traced out with sufficient precision — the general laws established on a firm 

 basis — the nomenclature framed with logical exactness — the facts consistent with 

 each other, and presented in a scientific and luminous form. Thus a philosopher, 

 like Sir Humphrey Davy, who had contributed in so eminent a degree to bring the 

 science into this satisfactory condition, might, at the close of his career, have des- 

 paired of adding anything worthy of his name to the domain of chemistry, and 

 have sighed for other worlds to subdue. But there was a world almost as little 

 known to the chemists of that period as was the Western Hemisphere to the Mace- 

 donian Conqueror, — a World comprising an infinite variety of important products, 

 called into existence by the mysterious operation of the vital principle, ami therefore 

 placed, as was imagined, almost beyond the reach of experimental research. This 

 is the new World of Chemistry, which the Continental philosophers in the first in- 

 stance, and subsequently those of our own country, have during the last twenty 

 years been busy in exploring, and by so doing have not only bridged over the Gulf 

 which had before separated by an impassable barrier the kingdoms of inorganic and 

 of organic nature, but also have added provinces as extensive and as fertile as those 

 we were in possession of before, to the partrimony of Science. 



It is indeed singular, that whilst the supposed elements of mineral bodies are 

 very numerous, the combinations between them should be comparatively few ; 

 whereas amongst those of vegetable and animal origin, where the ultimate ele- 

 ments are so limited in point of number, the combinations which they form appear 

 almost infinite. Carbon and hydrogen, for instance, constitute, as it were, the key- 

 stone of every organic fabric; whilst oxygen, nitrogen, and less frequently sulphur 

 and phosphorus, serve almost alone to build up their superstructure. And yet 

 what an infinity of products is brought about by ringing the changes upon this scan- 

 ty alphabet! Even one series of bodies alone, that known by the name of the 

 Fatty Acids, comprises several hundred well-ascertained combinations, founded 

 however upon a single class of hydro-carbons or compound radicals, in which the 

 carbon and hydrogen stand to each other in equal atomic proportions, and are in 

 each case acidified by the same number of equivalents of oxygen. These acids are 

 all monobasic, or combine with only one proportion of base ; but add to any one 

 of them two equivalents of carbonic acid, and you obtain a member of a second 

 series, which is bibasic, or is capable of forming two classes of salts. The above 

 therefore constitute a double series, as it were, of organic acids, the members of 

 which are mutually related in the manner pointed out, and differ from each other 

 in their mode of combining according to the relation between their respective ele- 

 ments. But already, by the labours of Hofmann and of other chemists, two other 

 double series of acids, the one monobasic, the other bibasic, mutually related 

 exactly in the same manner as those above, have been brought to light ; each series 

 no doubt characterized by an equally numerous appendage of alcohols, of aethers, 

 and of aldehydes, to say nothing of the secondary compounds resulting from the 

 union of each of these bodies with others. 



Hence the more insight we obtain into the chemistry of organic substances the 

 more we become bewildered, with their complexity, and in investigating these phe- 



