W. Skey. — Formation and Constitution of Torhanite. 387 



evolved, the mineral loses the whole of it, even at common temperatures. 

 Now, I conceive water has relations to the so-termed hygroscopic substances, 

 similar to those ammonia sustains to argentic chloride ; it chemically combines 

 with these substances, and the compounds thus formed are not permanent, 

 except, at a temperature not higher, and a tension of aqueous vapour not less, 

 than that at which they were produced. 



Lastly, as to a production of heat by the chemical combination of water 

 with the substances of plants, a combination brought about by changes 

 in the temperature of the air, or in the tension of its vapour, this is no doubt 

 a very useful provision for preventing atmospheric changes of this nature 

 affecting the vegetable world abruptly.* 



Art. LXII. — Notes on the Formation and Constitution of Torhanite and 

 similar Minerals. By William Skey, Analyist to the Geological Survey 

 of New Zealand. 



[Read before the Wellington Philosophical Society, 29th August, 1874.] 

 In prosecuting experiments, previously detailed, upon the evolution of heat 

 caused by mixing dry clay with various liquids, I noticed such an increase of 

 temperature in the case of petroleum that I suspected an absorption of a 

 portion of the matters dissolved in this liquid had occurred, and so was led to 

 investigate the matter further, when the following results were obtained : — 

 (1.) That our commercial kerosenes are nearly or quite decolorised by 

 mixing them with dry clay, and our best native petroleum greatly 

 modified. 

 (2.) That this process is very much quicker when the clay used has been 



dried at 100° or so C. 

 (3.) That in such a case the clay, if white, acquires a rose and afterwards 



a black colour, while its streak is light brown. 

 (4.) That torhanite has the same effect as clay. 

 (5.) That the coals I have examined, whether hydrous or anhydrous, do 



not appear to exercise any absorbent action upon the petroleum oils. 

 (6.) That the same is true of diatomaceous earth (dry), carbonate of lime, 

 and gypsum, hydrous or anhydrous, also pumice-stone and pipe-clay 

 (ignited). 

 (7.) That kerosene which has been completely decolorised by clay, when 

 heated to 100° to 150° C, blackens clay, but has no such effect upon 

 other porous substances, as gypsum, or prepared silica. 



* As I have since ascertained tkat heat is also evolved during tke hydration of 

 anhydrous wool, it is probable that we have ia this a provision of the same nature for use 

 in the animal world too. — W. S,, 23rd April, 1875. 



