XVII. 



THE CONSTITUTION AND EQUIVALENT 

 VOLUME OF MINERAL SPECIES. 



(1853-1863.) 



A paper with the above title, of which the introduction and an analysis are given 

 below, appeared in the American Journal of Science for September, 1853. In the 

 Proceedings of the American Association for the Advancement of Science for 1854, 

 the same subject is continued in an essay entitled Illustrations of Chemical Homol- 

 ogy. From the author's abstract of this, which appeared in the American Journal 

 of Science for September, 1854, some extracts are here given, in which will be found 

 his views on the constitution of the feldspars, since adopted by Tschermak, and gen- 

 erally ascribed to him. Further illustrations are given by extracts from a later paper 

 by the author in the Compte Rendu of the French Academy of Sciences for June 29, 

 1863, on saussurite and related minerals. Some general conclusions in accordance 

 with the views here expressed will be found in Paper XIX. of the present volume. 



IN a recent paper [XVI. of the present volume] we endeav- 

 ored to lay down some principles which may serve as the basis 

 of a sound theory of chemistry. Having explained the nature 

 of chemical changes, and the laws of combination, we showed 

 that the volumes of the uniting species are always merged in 

 that of the new one, so that the atomic theory, as applied by 

 Dalton, which makes combination consist in juxtaposition, is 

 untenable. It was further asserted that the simple relations 

 of volumes which Gay Lussac pointed out in the chemical 

 changes of gases apply to all liquid and solid species, thus 

 leading the way to a correct understanding of the equivalent 

 volumes of the latter. While chemists have not hesitated to 

 assign high equivalents to bodies of the carbon series, they 

 have been inclined to make the equivalent weights of denser 

 mineral species correspond to formulas representing the simplest 

 possible ratios. We endeavored, from a consideration of the 

 theory of equivalent volumes, to point out the errors to which 



