Catalytic Phanometia with Allotropy. 259 



t emperatures at which these elements would not of themselves 

 combine. And it has been ascertained by myself, that common 

 oxygen in contact with these metals, when they are in a finely- 

 i ivided condition, turns tincture of guaiacum to a deep blue. 

 Mercury also exhibits the same comportment ; and since, from 

 its fluid condition, contact between it, oxygen, and oxidizable 

 substances is very readily and completely effected, we can pro- 

 duce many oxidizing actions better under the influence of this 

 metal than even with gold, silver, &c. 



Freshly-prepared tincture of guaiacum shaken with chemically 

 pure mercury and common oxygen is instantaneously coloured 

 dark blue. Water rendered bluish by indigo solution is deco- 

 lorized by similar treatment. Aqueous hydrochloric, hydro- 

 bromic, hydriodic, hydrosulphuric, and hydrocyanic acids, give 

 up their hydrogen with greater or less rapidity to free oxygen 

 when in contact with mercury, with the formation of chloride, 

 bromide, iodide, sulphide, and cyanide of mercury. 



By shaking a solution of iodide of potassium with mercury and 

 oxygen gas, iodide of mercury and potassium is produced along 

 with free potash, &c. These and other oxidizing actions effected 

 by means of mercury, show in the most evident manner the che- 

 mically exciting influence which this metal exerts upon common 

 oxygen, — in other words, that mercury puts this gas in a 

 condition in which it acts chemically, like the oxygen changed 

 by electricity or phosphorus. From which fact we may certainly 

 be allowed to draw the conclusion, that the catalytic actions of 

 mercury which we have mentioned depend, just as do those of 

 platinum, gold, phosphorus, &c., upon an allotropizing influence 

 which this substance exerts upon common oxygen. 



With respect to their capacity of producing a great change in 

 the chemical condition of common oxygen, there is a tolerably 

 numerous class of substances which are of the greatest import- 

 ance in a theoretical point of view, and to which we must on that 

 account devote our especial attention. These are such substances 

 as associate themselves very readily with common oxygen, but in 

 so doing change it in such a manner that it may be' transferred 

 with ease from this combination to other oxidizable substances ; 

 that is, it exhibits a relation quite similar to that which marks 

 oxygen modifled by electricity or phosphorus. 



By far the most remarkable substance of this kind is deutoxide 

 of nitrogen (NO^), which even in the cold and in the dark unites 

 with two equivalents of common oxygen to form the so-called 

 hyponitric acid. Of this acid we know that it very readily 

 gives up lialf its proportion of oxygen to a great number of oxidi- 

 zable substances, that is, it comports itself as an eminently 

 oxidizing agent. It readily decomposes indigo-bluc dissolved in 



T2 



