650 REPORT— 1895. 



Like many other great discoveries iu science, the artificial formation of natural 

 products began, as in the case of alcohol and urea, with observations arising from 

 experiments not pi-imarily du'ected to this end. It was not till the theory of 

 chemical structure had risen to the rank of a scientific guide that the more com- 

 plicated syntheses were rendered possible by more exact methods. We justly 

 credit structural chemistry with these triumphant achievements. In arriving at 

 such results any defects in the theory of structure are put out of consideration 

 because— and this point must never be lost sight of — all doubt as to the possibility 

 of this or that atomic grouping being stable is set aside at the outset by the actual 

 occurrence of the compound in nature. The investigator starts with the best of 

 all assurances. From the time of Wohler and Ilennell the course of discovery in 

 this field has gone steadily on. The announcement of a new synthesis has ceased 

 to produce that excitement which it did in the early days when the so-called 

 ' organic ' compounds were regarded as products of a special vital force. The in- 

 terest among the uninitiated now rises in proportion to the technical value of the 

 compound. The present list of 180 odd synthetical products comprises, among the 

 latest discoveries, gentisin, the colouring-matter of the gentian root {Gejrtiana 

 lutea), which has been prepared by Kostanecki and Tambor, and cafleine, synthe- 

 sised by Emil Fischer and liorenz Ach, starting from dimethylurea and malonic 

 acid. 



I have allowed myself no time for those prophetic flights of the imagination 

 which writers on this subject generally indulge iu. When we know more about 

 the structure of highly complex molecules, such as starch and albumin, we shall 

 probably be able to synthesise these compounds. It seems to me more important 

 just at present to come to an understanding as to what is meant by an organic 

 synthesis. There appears to be an impression among many chemists that a syn- 

 thesis is onl}' effected when a compound is built up from simpler molecides. If 

 the simpler molecules can be formed directly from their elements, then the syn- 

 thesis is considered to be complete. Thus urea is a complete synthetical product, 

 because we can make hydrogen cyanide from its elements : from this we can 

 prepare a cyanate, and finally urea. In dictionaries and text-books we find syn- 

 thetical processes generally separated from modes of formation, and the latter in 

 their turn kept distinct from methods of preparation. Tlie distinction between 

 formation and preparation is obviously a good one, because the latter has a 

 practical significance for the investigator. But the experience gained iu drawing 

 up the tables of synthesised compounds, to which I have referred, has resulted in 

 the conclusion that the terms ' synthesis ' and ' mode of formation ' have been 

 either unnecessarily confused or kept distinct without sufficient reason, and that it 

 is impossible now to draw a hard-and-fast line between them. Some recent 

 writers, such, for example, as Dr. Karl Elbs, iu his admirable work on this subject,' 

 have expanded the meaning of the word synthesis so as to comprise generally the 

 building up of organic molecules by the combination of carbon with carbon, with- 

 out reference to the circumstance whether the compound occiu's as a natural pro- 

 duct or not. But although this definition is sufficiently wide to cover the whole 

 field of the production of carbon compounds from less complex molecules, it is in 

 some respects too restricted, because it excludes such well-known cases as the for- 

 mation of hydrogen cj'anide from its elements, or of urea from ammonium cyanate. 

 1 should not consider the discussion of a mere question of terminology of sufficient 

 importance to occupy the attention of this Section were it not for a matter of 

 principle, and that a principle of the very greatest importance, which I believe to be 

 associated with a clear conception of chemical synthesis. The great interest of all 

 work in this field arises from our being able, by laboratory processes, to obtain 

 compounds which are also manufactured in nature's laboratory — the living 

 organism. It is in this direction that our science encroaches upon biology through 

 physiology. Now, if we confine the notion of synthesis to the building up of 

 molecules from simpler molecules or from atoms, we exclude one of nature's 



' Die synthetisclien Barstellungsmethoden der KoldenstoffverhiTidungen. Leipzig, 

 1889. 



I 



