8o8 THE POPULAR SCIENCE MONTHLY. 



most gifted pupil Mohs, the majority of mineralogists claimed mineral- 

 ogy to be a purely natural history science. They gave their attention, 

 as has been well said, entirely to " how the mineral looked" and not at 

 all to " what it was." On the other hand, the development of analyt- 

 ical chemistry by the labors of Klaproth and Berzelius led many to 

 take up mineralogy from a purely chemical stand-point. These two 

 schools working independently brought great confusion into the science. 

 The discoveries of Haiiy in crystallography, and especially his labors 

 in establishing a mathematical foundation for the geometrical form of 

 crystals, and the recognition that the constancy of form depended on 

 the constancy of the " integrant molecule," were steps which paved the 

 way for modern mineralogy. In this a union of all the physical, geo- 

 metrical, and chemical properties is required in order to determine the 

 true character of a mineral. 



Further, we are called upon to investigate the history of its origin, 

 its relation to associated species, the changes which it undergoes, and 

 the causes and results of these changes. Here we have to do largely 

 with both geology and chemistry. From this it becomes evident that 

 a much broader foundation is now required for the mineralogist than 

 in the early days of the century. The bearing of physics, geology, and 

 chemistry, in the study of the mineral kingdom, must be thoroughly 

 recognized and appreciated by every investigator who desires to con- 

 tribute to further progress. No mineralogist can expect to have a pro- 

 found knowledge in all these directions, but he must be at least capable 

 of intelligently applying to his subject the results obtained by experts 

 in these sciences. Mineralogy is deeply indebted to special investiga- 

 tors in all these departments. Without their co-operation it would 

 have been impossible to discover the relations of form and other phys- 

 ical characters with that fundamental arrangement of molecules whose 

 nature it is now admitted controls all the properties of a substance. 



The study of natural crystals has yielded rich material for the 

 physicist. In the department of optics it has given results from which . 

 many fundamental laws have been deduced ; and natural crystals, too, 

 have furnished, in many cases, the very apparatus which made investi- 

 gations possible. Some chemists claim that mineralogy is not at all a 

 science by itself, and constitutes only a small part of inorganic chem- 

 istry. It can be unquestionably conceded that a knowledge of chem- 

 istry is fundamental, and in consequence this claim has a certain plausi- 

 bility. On the other hand, we contend that it was largely the labors 

 of the mineralogists on the physical characters of minerals, and espe- 

 cially their demonstration of the relation of form to chemical composi- 

 tion, which finally awakened chemists to a more profound study of 

 their own subject. The law of isomorphism was discovered by a chem- 

 ist, whose training as an expert crystallographer in the examination of 

 natural crystals made it possible for him to recognize the wonderful 

 relation of form to composition. Dimorphism was first established 



