\^ Mr, Miller on th^ Production of Acetic Acid. [July^ 



JErp. 6. — Charcoal fropa the decomposition of indigo. The 

 heat volatilizes the pure indigo ; while the residue, after the 

 carburetted hydrogen gases, &c. have been consumed, is simply 

 carbonaceous matter. 



Gums are compounds of 



Oxygen, 



Hydrogen, 



Carbon. 



By heat amounting to redness, they are decomposed; the 

 oxygen and hydrogen gases, with a portion of tne carbon, suffer 

 combustion; while the other part remains behind, and is pre- 

 cisely similar to charcoal ; it frequently contains a notable quan- 

 tity of siliceous matter, together with the other impurities of 

 gums. 



In the simple experiment of exposing a heated coil of platinum 

 wire to the vapour arising from the evaporation of ether or 

 alcohol, when the metal effects the combination of the oxygen 

 and hydrogen gases from that substance so rapidly, that the whole 

 of the coil continues incandescent, water* seems to be produced ; 

 but as the temperature of the coil diminishes, the combination 

 still ensues, though less rapidly, and a blue sulphureous-like 

 flame appears waving round the wire. Acetic acid vapour is 

 now formed in considerable quantity. It speedily converts the 

 blue solution of litmus to a bright red, and by holding a wine- 

 glass over the wire, it will condense, and speedily moisten the? 

 interior. 



This blue flame and acetic acid are produced in the following 

 experiments. 



Ether, alcohol, volatile oils, were the fluids over which these 

 substances were held, having been previously heated to redness 

 in the flame of a spirit-lamp. 



1 



I In carbonaceous expe- 



1 rimente. 



J 



pments 



♦ Although a solution of litmus is well known to be a most delicate test for acidity, 

 yet in this experiment its blue colour remained unimpaired, and the liquid produced by 

 the condensatioji of the vapours did not, as in the other instances, possess a sour taste, 

 so that I consider the fluid produced during the rapid combination to be water, arising 

 from the unfon of the hydrogen and oxygen gaiics of the ether and oxygen of the air. . 



