68 ESSAY V. 



added here, and the entire solution taking place without 

 heat. There occurs, indeed, here a circumstance, which 

 certainly proves that muriatic acid contains some phlogiston ; 

 a property which one should have attributed to the nitrous 

 acid, chemists having been of opinion that this principle 

 was present in a pretty large quantity, as one of its con- 

 stituent parts. But this we now reverse, and attribute 

 phlogiston to the muriatic acid. 



Muriatic acid, when digested in the cold with manganese, 

 assumes a dark brown colour (Sec. xv. (a)) ; for, since this 

 substance never affords a colourless solution without 

 phlogiston, the present solution will be either blue or red 

 (Sec. xiv. (4)), though the muriatic acid is capable of 

 dissolving manganese without the addition of the in- 

 flammable principle. In this case the colour has more 

 of brown than red, on account of the fine particles of the 

 manganese floating in the solution and not easily sinking 

 to the bottom ; for, without these particles, the solution is 

 red ; and red mixed with black yields a brown colour. 

 Manganese adheres here loosely to the muriatic acid; so 

 that it may be precipitated by water ; and the precipitate 

 shows the same properties as common manganese. When- 

 ever I exposed the mixture of manganese and muriatic acid 

 to digestion, an effervescence ensued with a smell of aqua 

 regia (Sec. vi. (&)). 



In order to set this new discovery in a clear light, I 

 tied to the neck of a retort, which contained a mixture of 

 manganese and muriatic acid, an empty bladder, and put 

 it into hot sand. An effervescence ensuing, the bladder was 

 filled. When the acid no longer occasioned any effervescence, 

 which was a sign of its saturation, I took the bladder off, 

 and found that the air had rendered the bladder yellow, as 

 nitrous acid would have done ; but there was not the least 



