156 Notes on the Chemical Subjects. 



and soda — the so-called water-glass — the alkali, to which the so- 

 lubility was due, being removed either by the slow action of the 

 weather, or by chemical agents specially employed for the pur- 

 pose. Thus superfluous and even injurious compounds were ne- 

 cessarily introduced, which, when removed by solution or eflflor- 

 escence, left the preservative coating porous and permeable. It 

 is now known, however, that pure silica may in certain cases be 

 dissolved in pure water; thus, if sulphide of silicium be dissolved 

 in water sulphuretted hydrogen is evolved, and silica remains 

 perfectly dissolved and in large amount ; or if pure water be 

 separated by a septum of parchment paper from a solution of 

 silicate of soda supersaturated with hydrochloric acid, after a few 

 days the hydrochloric acid and chloride of sodium passing through 

 the septum will leave an aqueous solution of silica on the other 

 side of the diaphragm. It is obvious that such a solution, which 

 may be prepared in many other ways than those here described, 

 will possess many advantages over a solution of water-glass, as a 

 preservative whether of wood or of stone. 



As aluminum from its malleability, ductility, tenacity, remark- 

 able lightness, beautiful colour and impassivity to the action of 

 those ever present chemical agents which so rapidly tarnish 

 silver and the commoner metals, promises to become of great 

 economic value, it is gratifying to find that the cost of its produc- 

 tion is rapidly diminishing, so that its price has descended from 

 £60 per lb. to 60s., at which price it is now furnished by the 

 Aluminum Works at Newcastle. 



Wood publishes in the Journal of the Franklin Institute the 

 following formula for a fusible metal which becomes perfectly 

 liquid at 180°F. ; cadmium 1 part, lead 6 parts, bismuth 7 parts. 

 This alloy has a bright metallic colour, is flexible in thin plates^ 

 is imperfectly malleable, and about as hard as coarse solder. 



ARTICLE XV.— Oil the date of the Report on the Geology of 

 Wisconsin^ noticed in this Journal, Vol. VI. p. 465. 

 In the number of this Journal for December last, there is a 

 notice of one sheet of Prof. Hall's recent Report on the Geology 

 of Wisconsin. On the 12th of March, 1862, two copies of the 

 same report were received at the office of the Geological Survey 

 of Canada, by mail. Both of these are dated January 1, 1861. 

 On one of the copies there are indorsed with pen and ink the 



