i62 Cincinnati Society of Natural History. 



workers, while the home of actual laboratory investigation is 

 in France, French writers give as explanation for this fact, 

 that they did not believe in collecting facts without co-ordina- 

 tion ; and their progressive genius led them to make hypoth- 

 eses and then to make experiments to prove these. Early in 

 the century Berthier and Ebelmen united their studies in 

 mineralogy and chemistry, and it is on this union that min- 

 eral synthesis as a science rests. 



The forces at work in the formation of minerals escaped 

 the observation of mineralogists, and were considered outside 

 the domain of chemistry. While this union is necessary for 

 a perfect synthesis, the two are essentially distinct, both in 

 methods and results. The chemist aims at a production of 

 the mineral as found in nature, while the mineralogist, in 

 addition, aims at an analogy with natural processes. Thus, 

 the chemist deposits copper by electrolysis, but this does not 

 show the origin of copper as found in nature. His task is 

 the easier, for he uses his reagents at pleasure, aiming only at 

 the final product. 



UTILITY. 



Having sketched the history and development of this work, 

 we may now consider the practical side, and see its aim and 

 what it has accomplished. 



1. Synthesis throws light on the mode of the natural forma- 

 tion of minerals and rocks. Thus, even down to late times, 

 water was considered to play an important part in the forma- 

 tion of a great number of volcanic rocks, and to be indispen- 

 sable in formation of basalt. Yet basalt and all the modern 

 volcanic rocks have been formed by purely igneous fusion. 



2. vSynthesis permits the determination of the exact compo- 

 sition of certain minerals impure in nature, notably, chiasto- 

 lite, garnet, staurolite, and a large number of metamorphic 

 minerals. Leucitc always shows in nature potash, lime, and 

 soda; yet the artificial mineral is made with no other base 

 than potash. Likewise, in case of oligoclase, labradorite, and 

 anorthite. 



3. The majority of the natural minerals are complex com- 

 binations, in which nian\- bodies are introduced by isomor- 



