30 Formation of Quartz Crystals, S^c.from Siliceous Solutions. 



thing at Vougy, but the geodes were composed of black oxide 

 of manganese lined with crystals of carbonate of lime. 



ft. Quartz Crystals formed iu the ohserver'^s presence from 

 a siliceous solution in a cavity. — As we have already given a 

 full account of this fact in this Journal, No. iii. p. 14], we 

 shall merely state that Mr B. F. Northrop, of Yale College, 

 found in the centre of a hornstone pebble a cavity three- 

 fourths of an inch long, by half an inch wide, a milky fluid, 

 like magnesia and water. While the rapid evaporation pro- 

 duced by a hot day was going on, " minute prismatic crystals 

 shot from the fluid even under the eye of the observer.'''' 

 These crystals were found to be quartz. In other cavities lined 

 with mammillary chalcedony, he found a white spongy depo- 

 s^lte resembling an earthy precipitate. 



3. J Gelatinous, Siliceous, and Impressible Mass found i7i 

 the cavities of a Pebble. — In the centre of a hornstone and chal- 

 cedony pebble, five inches by three, Mr Northrop found a cavity 

 1 J by 1 inch, nearly filled with a spongy siliceous deposite, which 

 was still moist to such a degree, " as to form a pulpy or gelatinous 

 mass, very soft and impressible, which also soon dried by the 

 intense heat of the weather.'''' A few crystals also shot here 

 and there as in the preceding cavity. " In a Jew cavities the 

 silicecms matter had concreted into well characterized mammil- 

 lary chalcedony.^'' — See this Journal, No. iii. p. 141. 



4. Hollow Balls containing from a pint to two quarts of a 

 milky fluid. — Mr E. Whiting of Newhaven saw in 1806, in 

 Georgia, hollow balls like bombshells, which had been pre- 

 viously found, and which were filled with a milky fluid so 

 nearly resembling white paint or white wash, that it was used 

 to whiten the fire-places and walls of the houses. These shells 

 were from 5-8ths to 3-4ths of an inch thick, and their crust 

 looked like an iron ore. Their capacity was from a pint to 

 two quarts. They were found in excavating a mill-dam in 

 Brier Creek, a stream which passes through Millhaven, and 

 flows into the Savannah river, and at the distance of two or 

 three miles from the road leading from Savannah to Augusta. 

 See Prof. Silliman's Journal, vol. viii. p. 285, and this Jour- 

 nal, No. iii. p. 142. 



5. Siliceous Tabasheer formed from a milky and viscid 



