1826.] Mr. Miller on the Production of Acetic Acid, 19 



1 1. Silver wire, a very beautiful experiment. The blue flame 

 and acid vapour are very evident in this experiment. 



12. Copper wire. 



13. Copper plate. ^ 



14. Iron wire. 



15. Steel wire. ' 



16. Copper and steel wires united. 



17. Brass wire. 



18. Brass foil, a very pleasing experiment. ■ 



19. Watch spring. 



20. Lead wire, a very beautiful cone of blue flame, plays for 

 some time round the coils of this wire. 



21. Dobereiner's pellets, containing spongy platinum, mixed 

 with day. These over ether and alcohol produce acetic acid:; 

 while by ajet of oxygen and hydrogen gases, water results. 



22. Glass tube. This is most certainly a curious experiment. 

 The tip of the glass rod held over the ether emits the blue flamfe 

 from the whole of its surface ; acetic acid formed in abundance. 



23. Piece of porcelain. 



24. Lime. This is a very beautiful experiment. The portion 

 next the ether seems to continue incandescent ; it emits a white 

 light very similar in appearance to that produced by the phos- 

 phorescence of certain substances. 



Acetic acid is a compound of 



Carbon, 

 Oxygen, 

 Hydrogen. 



Are those vapours of this acid (which condense in a cool glass 

 receiver hejd over the wire) formed by the union of the carbon 

 and hydrogen of the ether, with the oxygen of the air and ether? 

 or is carbonic acid gas first formed, and then by its uniting with 

 the hydrogen of the ether does it produce acetic acid? 



Brass, iron, and copper wires, as well as glass, lime, &c. 

 require to be heated to redness (in the dark), then transferred 

 speedily over the ether or alcohol, the blue flame instantly 

 appears, and will be visible for some time until the temperature 

 is too low to decompose the vapour. 



Lead wire must be heated until it is just ready to melt, and 

 then quickly held over the ether. 



The reason whjr brass, iron, copper, &c. do not effect the 

 combination sufficiently rapidly so as to arrive at incandescence 

 is, because the heat generated by the union of the gases is as 

 quickly conducted away by the metal, so that the heat is not 

 retained, as is the case in platinum, palladium, &c. where at 

 that part which favours the union, it is rendered sensible by its 

 incandescence to the eye-sight, but that copper, iron, &c. effect 

 the combination of the two gases from the above-mentioned 



c2 



