dtids. 157 



The nitric acid is found in very small quanti- 

 ties in the air in the real acid state. But it ap- 

 pears, that the whole that we possess comes ori- 

 ginally from the atmosphere; for saltpetre, or 

 nitrat of potass, whence it is prepared, is ob- 

 tained by lixiviating (or washing) earth and rub- 

 bish which has been long exposed to the joint 

 action of the atmosphere and animal effluvia. 

 Yet it appears to be the impregnated calcareous 

 matter that determines the formation of the salts 

 found in it, and not an acid ready formed that 

 finds out and seizes the former. 



3dly, The muriatic, or, according to the more 

 modern nomenclature, the hydrochloric acid., in 

 its strongest state, is a light-yellowish-coloured 

 fluid, and emits fumes when exposed to the air, 

 which do not tinge the air red, but impart to it a 

 mistiness. These fumes are noxious to the lungs. 

 Its smell resembles that of burning soot. 



Now, equal volumes of hydrogen and chlorine 

 gas being mixed and exposed to light, they com- 

 bine, and produce a sour compound, which is 

 the gas we are now speaking of. Muriatic acid 

 gas is therefore a combination of hydrogen with 

 another gaseous substance. 



Chlorine, is obtained by distillation from the 

 oxide of manganese and substances containing 

 the muriatic acid. It was named by Scheele, 

 its discoverer, dephlogisticated muriatic acid, and 

 by the French chemists, who considered it as a 



