xi MURIATIC ACID AND CHLORINE 225 



by the action of chlorine on an excess of mercury is an 

 insoluble white powder known as CALOMEL. It contains 

 more mercury and less chlorine than the CORROSIVE 

 SUBLIMATE which is formed when the chlorine is in excess. 



Compounds of chlorine with the metals. Davy's view that 

 chlorine was an element involved also a new conception as 

 to the nature of the muriates, or chlorides. Most of the 

 salts that had been investigated contained a fixed, earthy 

 BASE, usually a metallic oxide, in combination with a volatile 

 ACID, usually the oxide of a non-metal such as carbon, 

 nitrogen, sulphur or phosphorus. These salts were, there- 

 fore, BINARY COMPOUNDS of the tWO Oxides Or TERNARY 



COMPOUNDS of metal, non-metal and oxygen, thus : 



= /METAL 



CHALK = -( \OXYGEN 



~ \CARBON 



C /- \ p -p Tf TJ 



COPPER OXIDE 

 v SULPHURIC ANHYDRIDE = ( SULpHUR 



The muriates on the other hand, as Scheele had observed, 

 were formed by the direct combination of chlorine with the 

 metals. 



In order to maintain the analogy with the sulphates, 

 phosphates, etc., the French chemists assumed a further 

 sub-division of the chlorine, thus : 



MURIATE 



LEAD = LEAD 



OF LEAD I CHLORINE = I OXYGEN 



\ UNKNOWN MURIATIC RADICAL 



Davy showed that this view was not justified by any 

 experimental evidence. He suggested, as a more reason- 

 able hypothesis, that chlorine " may possibly belong to the 

 same class of bodies as oxygen " (A.C.R. IX. 33), and that 



Q 



