2 DR BREWSTER on the Existence of Two New Fluids 



Cymophane, Peridot, Feldspar, and in the following crystals form- 

 ed by aqueous solution. 



Sulphate of Iron. Sulphate of Ammonia and Magnesia. 



Sulphate of Zinc. Nitrate of Silver. 



Sulphate of Copper. Nitrate of Strontian. 



Sulphate of Nickel. Muriate of Barytes. 



Sulphate of Soda. Acetate of Lead. 



Sulphate of Magnesia. Oxymuriate of Potash. 



Sulphate of Ammonia. Muriate of Barytes. 



Sulphate of Magnesia and Iron. Oxalic Acid. 



Sulphate of Soda and Magnesia. Tartrate of Potash and Soda. 



Sulphate of Alumine and Ammonia. Carbonate of Potash. 



Being persuaded, from these results, .that water will be found 

 in every crystal deposited from a solution, I was next desirous of 

 finding it in crystals formed by heat, or by sublimation ; but in 

 no case have I been able to discover the slightest trace of its ex- 

 istence ; and, in the absence of all other information on the sub- 

 ject, I considered this result as highly favourable to the aqueous 

 origin of those minerals in which water has been discovered. 



Sir HUMPHRY DAVY was, we believe, the first philosopher 

 who conceived the idea of opening the cavities of crystals, and of 

 examining chemically the nature of the fluid which they contain, 

 and of the gas by which it is sometimes accompanied ; and the 

 experiments which he undertook for this purpose, were con- 

 ducted with that sagacity and address which characterise all his 

 labours. Upon opening the cavities in a variety of rock-crystals 

 of different localities, and collecting the fluids in fine capillary 

 tubes, he discovered, that, in every case, except one, the fluid 

 was Water nearly pure ; that, in this single case, it seemed to 

 be Naphtha ; that the gas was in two cases Azote, and was about 

 65 times more rare than that of the atmosphere ; that, in one 

 case, the gas (the nature of which is not mentioned) was compres- 



