near the end of the preceding one, the important work has been done since the year 1850, which date may be taken as the beginning of synthetic mineralogy. Through the eighteenth century came many suggestions on the artificial formation of minerals, followed by the crude attempts at the reproduction of petrifactions and incrustations. Unsuccessful attempts finally led to the successful reproduction of marble by James Hall in 1801, the first mineralogical synthesis and the beginning of experimental geology.
The first workers, as would be expected, were chemists; among whom Daubrée stands pre-eminent. When the mineralogists joined in the work, it was found that the conditions governing the chemist's experiments differed from those they could apply. It was early discovered that the forces at work in the formation of minerals escaped the observation of the mineralogists, and, though observed, were considered outside the domain of chemistry. The chemist's aim was to form a mineral like the one found in Nature; but the mineralogist, in addition, must use analogous processes to. those in Nature. In the chemical sense if the artificial product had the correct chemical composition, reaction, physical properties, such as density, boiling point, and the like, the synthesis was complete. On the other hand, in the mineralogical sense there must be also an entire agreement of the resulting product with the natural one morphologically. It must have the crystal form and also the characteristic type as in Nature, with the same optical properties, in order to be perfect. Thus the chemist could deposit copper by electrolysis, like the copper found in Nature; but this does not show the origin of copper in Nature. His task is the easier one, for he uses his reagents at pleasure, aiming only at the final product. In the course of time, the chemist and mineralogist seeing their mutual needs, united their efforts, and it is on this union that mineral synthesis as a science rests.
The cause of the long delay in the progress of this line of study was the idea, so firmly fixed in the minds of the old chemists, that Nature worked by mysterious means and had at her disposal indefinite time and enormous masses with supposed forces out of all proportion to those used in the laboratory. Then how was it possible in a crucible with a certain number of grammes of matter to reproduce a crystal of the same kind and association as those which the volcano ejected—a crucible a million times larger and under enormous pressure and temperature? The answer seemed too clear to even admit of such a vain attempt; they could not see the law of proportion which existed there, but it only needed progressive men to discover it. Even when this law was discovered, the crude means and limited experience at hand