1912.] BOGERT— CARBON COMPOUNDS. 255 



to medicine, until the coalescence of the two sciences appeared 

 practically complete. And thus arose the period of iatro chemistry, 

 when chemistry, which had long been looked upon as a valuable 

 helpmeet to medicine, came to be regarded as the basis of the entire 

 medical art. 



Although in this period the chief development was again along 

 the mineral side, probably because of the relatively greater simplicity 

 and stability of these preparations, still no little organic investi- 

 gation was conducted and a number of new compounds were added 

 to the science. Little progress was made in gaining a truer insight 

 into the character of chemical compounds, and hence no important 

 changes in classification appear. Paracelsus himself, the founder of 

 the iatro-chemical school, adopted Basil Valentine's three elements 

 (sulfur, mercury and salt) as the basis of his doctrines. 



By the middle of the seventeenth century, chemistry awakened 

 to the fact that it had a destiny of its own to realize, struggled to 

 its feet and, refusing longer to be supported by other sciences, 

 started forward, to be sure rather unsteadily and uncertainly at first, 

 but with the firm determination to do something for itself. 



The history of chemistry proper begins with Robert Boyle about 

 1660, who taught that its main object was the determination of the 

 composition of matter. Through his labors, and those of Rouelle 

 and others, the terms " element " and " chemical compound " were 

 more fully explained and appreciated ; nevertheless many of their 

 colleagues still adhered to the old alchemical or even the Aristotelian 

 elements. Kopp, in his " Geschichte der Chemie," gives an excel- 

 lent picture of the epoch-marking effect of Boyle's ideas : 



" What a contrast is exhibited between the ancient idea of the cause of 

 difference in various forms of matter and that which obtained at the time of 

 Boyle! If we consider these two opposite conceptions historically, and the 

 transition from the one to the other, they appear like two totally dissimilar 

 pictures ; but, like dissolving views, changing the one into the other by slow 

 degrees. In the first place we have the AristoteHan idea, according to which, 

 matter itself devoid of properties, becomes endowed with characteristic 

 qualities by the addition of properties, and forms, when invested with these 

 properties, the various substances known in nature; then this idea passes 

 gradually into that of the alchemists, but becomes confused in the transition, 

 inasmuch as the differences of physical condition and properties are no 



