Page:Popular Science Monthly Volume 7.djvu/748

728 to life, tacitly accepted it. Chemical substances which are produced under the mysterious influence of life, in the dark, unfathomed cavities of living organisms, cannot be produced by the hand of the mortal chemist. This was the conclusion which grew to be a dogma. and was used as a kind of ex post facto argument in favor of certain views in regard to the so-called "vital force."

But its influence did not cease here. Having worked so beneficially as an important link in a chain of retrograde logical sequences, it was afterward made a starting-point for other lines of argument. It was employed in religious and purely philosophical discussions, and assisted in the establishment of subsequent illogical conclusions.

As these discussions were taking place, the chemist quietly continued his strange dealings with the elements. Discovery followed discovery, until the fact could no longer be doubted that the dogma must fall. Its fall was, however, not the matter of a moment. It received repeated blows before it gave up its existence. Its place has been taken by an hypothetical statement founded upon a large array of facts, viz.: every chemical body, no matter of how complicated a structure, or what its nature may be, will probably, in good time, be prepared artificially in the chemist's laboratory. And this statement becomes more and more probable every day. Already a large number of the compounds, the formation of which was formerly supposed to be dependent upon the action of the vital force, have been reproduced entirely independently of any suspicion of the action of this force; and thousands of other analogous compounds which have never been found in plant nor animal are now known to us. Let us look briefly at some of the steps that were taken in this advance of opinion.

In the year 1828 Wöhler made the first observation bearing directly upon this subject. A few years earlier he had discovered cyanic acid, and he was now engaged in the thorough investigation of this acid. He prepared its ammonium salt, and, on evaporating the aqueous solution of the salt, he noticed the formation of large, well-developed crystals that in every respect resembled urea. Urea was well known, but had, up to that time, only been found among the products formed in animal bodies. Its existence was, in accordance with the then prevalent views, supposed to be due to the inexplicable action of the vital force. A careful examination failed to disclose any points of difference between the two bodies, and Wöhler was forced to the conclusion that at least one organic substance could be prepared outside of the organism.

But this by no means brought about a change of views. The upholders of the old dogma immediately found relief which was apparently satisfactory. Cyanogen compounds, of course including cyanic acid, had only been prepared from substances which had had their origin in the organs of animals, and, although these original