Dr THOMAS THOMSON on some Experiments on Gold. 29 



composition of a chloride from that of an oxide. The peroxide 

 of gold, containing 3 atoms of oxygen, one would have been dis- 

 posed to infer, that the chloride would also contain three atoms 

 of chlorine. Yet it contains only two atoms. This want of 

 coincidence between the peroxide and chloride of gold, is pro- 

 bably the reason why the muriate of gold cannot be converted 

 into a chloride by heat ; at least all my attempts to obtain a 

 chloride by that process, have ended in disappointment. In what 

 manner the change takes place in the atomic proportions, when 

 common salt is added to the muriate, it is not easy to conceive ; 

 but the experiments which I have related in this paper, and in 

 my " Attempt," leave, I conceive, no doubt that the conversion 

 from muriate to chloride actually takes place. 



5. There is an analogy visible between the muriate of gold 

 and the hydrocyanate of potash. Both of these salts are very 

 easily decomposed in their isolated state ; but when we combine 

 the former with an alkaline muriate, or the latter with a metal- 

 lic hydrocyanate, they become both very permanent and diffi- 

 cultly decomposed salts. 



6. It has been lately maintained by BERZELIUS, that muriatic 

 acid is incapable of combining with metallic oxides ; that no mu- 

 riates exist, but merely chlorides, or compounds of chlorine and 

 the metal, united to a certain quantity of water. With regard to 

 the greater number of these compounds, it is a matter of indiffer- 

 ence which of the two views we take. Thus we may either 

 consider what is usually called muriate of barytes, as a chloride 

 or a muriate. In the first case, the crystals of it will be com- 

 posed of 



1 atom chloride of barium, 13 '25 



2 atoms water, 2- 25 



15.50 



