1913-] ROGERS— THE NOMENCLATURE OF MINERALS. 613 



serve the purpose of convenience. For example, the name for the 

 basic calcium phosphate for which I recently proposed the name 

 voelckerite^* would be something like calcium oxy-phosphapatate. 



Arbitrary names I believe are preferable to names such as those 

 proposed by Washington. My reasons are as follows : 



1. Arbitrary names are stable; there is no necessity for change 

 because of an incorrect analysis. 



2. Any name of a new mineral that is proposed stands for the 

 predominant molecule whatever its isomorphous relations may be. 



3. Arbitrary names are more convenient than other names be- 

 cause they are shorter. 



4. The present names are to a large extent retained and very few 

 names will be necessary. 



Most of the present names are so well established by long asso- 

 ciation that it will be almost impossible to substitute other names 

 for them. The law of priority, with certain limitations,^^ holds in 

 mineralogy as in zoology and botany. 



Only the professional mineralogist would be apt to use Wash- 

 ington's system, but to him the arbitrary names are not objectionable. 



There is one apparent objection that may be urged against my 

 plan. A quantitative chemical analysis will often be necessary to 

 place and name a mineral that is near the dividing line between two 

 isomorphous compounds. This is unfortunate from the standpoint 

 of determinative mineralogy but it is no real objection. It goes 

 without saying that accuracy of definition is based upon accurate 

 work which must often be quantitative in character. As Miers^^ 

 says "... it cannot be too strongly impressed upon the student at 

 the outset that scientific mineralogy is based upon accurate measure- 

 ments and determinations." 



There are several points to mention in connection with the record- 

 ing of chemical analyses of minerals. I think it is well, as I have 

 done in a recent text-book,^'^ to record mineral analyses in the form 

 of metals and acid radicals instead of the usual form of oxids. The 



^* Amer. Jour. Set. (4), Vol. 33, p. 475, 1912. 



15 Dana, " System of Mineralogy," 6th ed., p. xliii, 1892. 



16 " Mineralogy," p. v. 



1^ " Introduction to the Study of Minerals," New York, 1912. 



