18 Sketch of the latest Iviprovements [Jan, 



the metallic state ; for it is evident that this mercury must have 

 united with exactly the quantity of oxygen which the gold con- 

 tained. In one experiment, 14*29 of mercury precipitated 9'355 

 of gold ; in another, 9'95 of mercury precipitated 6 55/ of gold. 

 According to these experiments, it appears that 15 '9 12 of gold, 

 when in the state of peroxide, contain just as much oxygen as 24*24 

 of mercury, when in the state of peroxide. But according to the 

 experiments of Sefstrom, whom Berzelius follows, peroxide of 

 mercury is composed of 100 mercury + 7" 9 oxygen. Hence he 

 reckons the peroxide of gold a compound of 



Gold 89*225 100*000 



Oxygen 10*775 12*0/7 



100*000 



If we consider the red oxide of mercury as composed of 100 

 metal + 8 oxygen, as I have done in my table inserted in the 

 second volume of the Annals of Philosophy, in that case we obtain 

 the composition of peroxide of gold as follows : — 



Gold 89*137 100*000 



Oxygen 10*863 12*187 



100*000 



This last statement agrees better with the experiments of Ober- 

 kampf than that of Berzelius. Oberkampf found sulphuret of gold 

 composed of 100 gold and 24*39 sulphur. Now if an atom of 

 sulphur weigh twice as much as an atom of oxygen, it follows that 

 peroxide of gold ought to be composed of 100 gold + 12*195 

 oxygen. 



When muriate of gold is exposed to a moderate heat upon a 

 sand-bath, as long as it gives out chlorine gas it assumes a strong 

 yellow colour, and becomes insoluble in water ; or if the heat has 

 not been continued long enough, only the portion of muriate of 

 gold which is unaltered is dissolved, while that which has acquired a 

 strong yellow colour remains undissolved. If heat be applied to 

 this substance, or if it be simply exposed to the light of day, it is 

 decomposed, and converted into metallic gold and permuriate of 

 gold. According to Berzelius, the straw-coloured substance is a 

 promuriate of gold. Heat or light deprives one portion of the 

 protoxide of the whole of its oxygen, this oxygen unites with the 

 remaining protoxide, and, converting it into peroxide, permuriate 

 of gold is again formed. Now he found by experiment that in this 

 case two-thirds of the gold are reduced to the metallic state, while 

 one-third is converted into peroxide ; so that the protoxide of gold 

 contains just one-third of the oxygen hi the peroxide. 



I may just observe, that these conclusions are not quite free from 

 objections. I myself think it not unlikely that no oxygen is present 

 ia either of these salts. This, however, does not hinder the calcu- 



