Mineralogy and Geology. 273 
other things he plainly puts forward the view that many of the sub- 
stances now regarded as elements contain hydrogen; and suggests that, 
even if the elements which are combined with hydrogen in these com- 
pounds do not exist in the free state on our earth, they may possibly 
exist in that state in other parts of the universe. 
No one will maintain that the bodies which we now call elements are 
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however, of further knowledge, we may hold fast by the principle an- 
| —_—*‘ROUunced by Dalton, “ that a substance, till it is decomposed, must be re- 
. = according to the just logic of chemistry, as an elementary sub- 
. ance, 
II. MINERALOGY AND GEOLOGY. 
and including a great variety of species among Crinoids, 1 
Acephals, Gasteropods, Orthocerata, Trilobites and Eurypterids, all 
f cart . The fourth volume, as the 
— to the Brachiopods, deferring to a future volume the remainder of the 
Pecies, 
Terebratula, Cryptonella, Centronella, Tropidoleptus, Vitulina, 
AM. Jour. Sc1.—Szconp SzRrzs, Vou. XLIV, No. 131.—Supr., 1867. 
| 35 
