Ford— Growth of Mineralogy, 1818 to 1918. 247 



practically no description of optical characters was 

 attempted, and only occasionally were the crystals of a 

 mineral mentioned. J. D. Dana was almost the only 

 writer who constantly endeavored to discover the funda- 

 mental characters and relationships in minerals. He 

 published many articles in these years which were con- 

 cerned chiefly with the classification and grouping of 

 minerals, with similarities in the crystal forms of dif- 

 ferent species, with relations between chemical compo- 

 sition and crystal form, chemical formulas, mineral 

 nomenclature, etc. The following titles give an idea of 

 the character of the more important series of articles by 

 him which belong to this category: On the isomorphism 

 and atomic volume of some minerals (9, 220, 1850) ; vari- 

 ous notes and articles on homceomorphism of minerals 

 (17, 85, 86, 210, 430; 18, 35, 131, 1854) ; on a connection 

 between crystalline form and chemical constitution, with 

 some inferences therefrom (44, 89, 252, 398, 1867). 



A great many new mineral names were proposed 

 between 1850 and 1870, a large number of which have con- 

 tinued to be well-recognized species. But there was 

 also a tendency, which has not wholly disappeared even 

 now, to base a mineral determination upon insufficient 

 evidence, and to propose a new species with but little 

 justification for it. In this connection a quotation from 

 the introduction by J. D. Dana to the 3rd Supplement to 

 the System of Mineralogy (4th edition) published in this 

 Journal (22, page 246, 1856), will be of interest. He 

 says : 



"It is a matter of regret, that mineral species are so often 

 brought out, especially in this country, without sufficient inves- 

 tigation and full description. It is not meeting the just 

 demands of the science of mineralogy to say that a mineral has 

 probably certain constituents, or to state the composition in a 

 general way without a complete and detailed analysis, especially 

 when there are no crystallographic characters to afford the 

 species a good foundation. We have a right to demand that 

 those who name species, should use all the means the science of 

 the age admits of, to prove that the species is one that nature 

 will own, for only such belong to science, and if enough of the 

 material has not been found for a good description there is not 

 enough to authorize the introduction of a new name in the 

 science. The publication of factitious species, in whatever 

 department of science, is progress not towards truth, but into 



