S. W. Tyler and C, U. Shepard on Rahtite, etc. 209 
ascribed to the repulsive action of the heat-pulses taken up by the 
; : iderable depths below their surface; 
impulses exerted by electric currents (p. 65); the one, analogous 
to light, developing magnetic currents in groups of molecules, 
Molecules, compound, or simple, by an indirect expansive action. 
ew Haven, Jan. 15, 1866. 
—— 
Art, XXVIIL—Analyses of Rahtite, Mareylite and Moronolite ; 
by Mr. S. W. Tyrer, A.B., member of the Mining School of 
Freiberg, Saxony, with prefatory remarks ‘by Prof. CHARLES 
U. Sueparp. 
1. Rahtite.—This mineral was distinguished by me as a new 
Species in March, 1861, during a survey of the Ducktown copper 
mines, Tennessee, where it was found in the upper, decomposed 
Portions of the great copper-lodes, associated with melaconite 
and with various mixtures, of chalcopyrite, redruthite and mela- 
Conite, and also more rarely with galena and cuprite. ae al 
In structure it is quite massive, though at first inspection it 
Seems highly crystalline; but this deceptive eprestonee arises 
from its being traversed in all directions by slender prismatic 
Cavities imparted to it by some unknown mineral which has 
holly disappeared... The walls of these cells are polished and 
bright. The color of the mineral is dark lead-gray with a ba 
ness 
The following are Mr. Tyler’s description and analysis of the 
Specimen submitted to him by me for examination: “noe 
Aw. Jour. Sct.—Seconp Series, Vot. XLI, No. 122.— 1966. 
QT 
