242 PROCEEDINGS OF THE AMERICAN ACADEMY 



ingenious but arbitrary assumptions of numbers, that is to be found an 

 explanation of the results obtained by Playfair and Joule in comparing 

 the volumes of various solid species with that of ice, which they as- 

 sume to be represented by H O, instead of a high multiple of this for- 

 mula. The recent ingenious but fallacious speculations of Dr. Mac- 

 vicar, who has arbitrarily assumed comparatively high equivalent 

 weights for mineral species, and has then endeavored by conjectures as 

 to the architecture of crystalline molecules to establish relations between 

 his complex formulas and the regular solids of geometry, are curious 

 but unsuccessful attempts to solve some of the problems whose signifi- 

 cance I have here endeavored to set forth. I am convinced that no geo- 

 metrical groupings of atoms, such as are imagined by Macvicar and by 

 Gaudin, can ever give us an insight into the manner in which Nature 

 builds up her units, which is by interpenetration and identification, and 

 not by juxtaposition of the chemical elements. 



None of the above points are presented as new, though they are all, 

 I believe, original with myself, and have been from time to time brought 

 forward and maintained, with numerous illustrations, chiefly in the 

 American Journal of Science, since March, 1853, when my Essay on 

 the Theory of Chemical Changes, and on Equivalent Volumes, was 

 there published. I have, however, thought it well to present these 

 views to the Academy in a connected form, as exemplifying my notion 

 of some of the principles which must form the basis of a true minera- 

 logical classification. 



Mr. G. W. Hill presented a communication on the Inequali- 

 ties produced in the Moon's Motion by the secular variation 

 of the position of the Ecliptic. 



Five hundred and seventy-seventh Meeting. 



January 30, 1867. — Statute Meeting. 



The President in the chair. 



The Corresponding Secretary read a letter from Professor 

 A. C. Kendrick of Rochester, New York, in acknowledgment 

 of his election into the Academy. 



The President called the attention of the Academy to the 

 recent decease of M. Cousin of the Foreign Honorary Mem- 

 bers. 



