GEOLOGY. 291 



circumstances, crystallize and form the diamond. Unfortunately for 

 ine, however, I lost the precious drop in attempting to secure it. 



" A green tree, cut down and obliquely inserted in one of the conical 

 mounds, was so changed, in thirty-six hours, that its species would not 

 have been recognized, except from the portion projecting outside, around 

 which beautiful crystals of sulphur had already formed. 



" From the thermal exhalations and the amount of sulphur deposited, 

 it might be supposed that the progress of vegetation would be retarded. 

 But such is not the fact. On the contrary, it is greatly facilitated. 

 The Quercus sempcrvirens, or evergreen oak, nourishes in beauty within 

 fifty feet of the boiling and angry geysers. Maples and alders, from 

 one to two feet in diameter, grow within twenty or thirty feet of the 

 hottest steam-pipes. This, however, may be accounted for by the cold 

 surface water flowing down from the adjacent mountain. Multitudes 

 of grizzly bears make their beds on the warm grounds. Panthers, deer, 

 hares and squirrels, also take up their winter quarters in the very midst 

 of the geyser mounds. Farther down the stream, on the terraced banks 

 of the limpid Pluton, vegetation ' actually runs wild,' and the winter 

 months exhibit all the fancied freshness of primeval Eden. I have traced 

 the influence of this thermal action from two to three hundred miles on 

 the Pacific coast in California, but only in this place have I been per- 

 mitted to witness its astonishing intensity. The inetauiorphic action 

 going on is at this moment effecting important changes in the structure 

 and conformation of the rocky strata. It is not stationary, but appar- 

 ently moving slowly eastward in the Pluton valley. 



ARTIFICIAL TOPAZ.* ~-^ 



M. DAUBREE has communicated to the Paris Academy of Sciences 

 the results of some researches on the artificial formation of Topaz. Pure 

 alumina, previously calcined by a bright red heat, is submitted to the 

 action of a current of fluoride of silicon. After two exposures of this 

 kind, the alumina increased in weight 70 per cent. The product con- 

 tained fluorine, and, what was more, this fluorine is in such a state of 

 combination as not to be acted upon by boiling concentrated sulphuric 

 acid. By this characteristic alone, the substance produced offers a 

 great resemblance to topaz, the four constituent elements of which it 

 also contains. A quantitative analysis indicated its very near approach 

 to, if not identity with, topaz. Its specific gravity, which is 3.47, is 

 the same as that of natural topaz. 



CLINOCHLORE; A NEW SPECIES. 



MR. W. P. BLAKE, of the Yale Analytical Laboratory, has examined 

 the beautiful green foliated mineral from Chester County, Pa., which 

 has hitherto been supposed to be chlorite. On the examination by 

 polarized light, Mr. Blake finds that the mineral is biaxial, with a high 

 angle between the optic axes, being in one specimen 84 30', and in 



* See Annual of Scientific Discovery, 1850, p. 212, 1S51, p. 167. 



