COMMON SALT: HYDROCHLORIC ACID 



79 



downward displacement in C. Does the gas burn or support 

 the combustion of a taper ? Remove the delivery tube, cover 



Fig. 35. 



the orifice with a glass plate, insert in a trough of water, and 

 at the same instant remove the plate. Is the gas soluble in 

 water? Now cause the gas to bubble into water till a 

 saturated solution is obtained. Is the solution acid to litmus 

 and sour in taste ? Neutralise a little with caustic soda, and 

 evaporate. Are cubic crystals obtained having the taste of 

 comm.on salt ? 



By the early chemists all acids were supposed to be oxygen 

 compounds, and the acid from salt was called muriatic acid, 

 salt being supposed to be muriate of soda. The acid might, 

 however, be the hydrogen compound of a non-metallic 

 element, just as sulphuretted hydrogen, the solution of which 

 is also acid to litmus, is the hydrogen compound of sulphur. 

 In this case, common salt would be the compound of this 

 non-metallic element with sodium. This is now known to be 

 the case; the non-metallic element is chlorine^ the acid is 

 hydrogen chloride or hydrochloric acid, and " salt " is chloride 



