On Certain Cavities in Quartz, (^c. 139 



The solution from which the oxalate of lime had been thrown 

 down was treated with ammonia and phosphate of soda, without 

 having its transparency effected, whereby the absence of magne- 

 sia and lithia in the mineral was apparent. After several hours 

 standing, chloride of platina was added, which immediately gave 

 rise to the fine granular precipitate of the double salt of platino- 

 chloride of potassium. 



Whether the mineral contains soda as well as potassa, I am not 

 at present able to say. 



The following therefore is a summary of what I have been 

 able to infer respecting the chemical constitution of the mineral 

 under consideration : 



Silica, - - - - 56.00 



Lime, - - - - 28.33 



Alumina, - - - - 1.70 



Yttria? - - - - 0.85 



Potassa (perhaps with soda) and loss, 5.12 



Water, - - - - 8.00 



100. 

 The above result favors the idea of the following atomic ar- 

 rangement : viz. 



10 Ca Si='+K3 + /? Al +1y Jsi^'+H. 



Art. XII. — On Certain Cavities in Quaj'tz, 6^c., in a letter to 

 the Editor, from Dr. Washington L. Atlee, dated Lancaster, 

 Penn., Dec. 9, 1837. 



Dear Sir — Within our city and its vicinity I have picked up 

 several anomalous specimens of quartz, bearing the impressions 

 of the different faces and angles of crystals, that afterwards be- 

 came detached. In most of these specimens these impressions 

 are deep, giving a cellular aspect to the whole mass. In some, 

 they are tabular and evidently rhombic, or portions of rhombs, 

 having their various angles and inclined feces accurately defined. 

 In others, the indentations are principally pyramidal and cuneiform, 

 with here and there a tabular rhombic impression. In one large 

 and beautiful specimen, the cells are much larger, and more uni- 



