Ch emu o- Galvanic Observations. 13? 



changed in proportion as the water evaposated, and nothing 

 else remained than a blackish oxide. 



The author concludes from these facts, that iron positively 

 galvanized in water does not there experience its greatest 

 possible degree of oxidation, and that the colour which it ac- 

 quires happens from its particular combination with water; 

 a combination hitherto unknown or neglected by chemists. 



The negative wire was covered after several hours Gal- 

 vanism with a portion of the oxide of hydrogenated iron 

 which came from the positive pole. But this oxide was der 

 composed there, converted into alkaline oxide of iron of a 

 yellow colour, and very soluble in water. It is this singular 

 combination which occasions the yellow tint of the water 

 of the recipient, a liquid thus converted into a true alkaline 

 tincture of mars. 



Towards the extremity of the wire a portion of the hydro- 

 genated oxide of iron became blackened, and converted into 

 hydrogenated iron of the deepest black. 



The yellow water in this experiment did not form blue 

 with the prussiate of potash, and scarcely greened the purple 

 tincture of althea, which the author employed as the most 

 sensible re-agent in the presence of the acids or the alkalis. 



§ VIII. 



Disengagement of the Carbonate of Soda in pure Water 

 galvanized ivith Charcoal', Hydrogenated Charcoal; Pro- 

 ject of a solid Vegetable Pile. 



The author determined to examine what was the change 

 which water underwent when galvanized by the interme- 

 dium of charcoal. He took out of a burning furnace some 

 pieces of charcoal of about an inch and a half in length, 

 and, after having extinguished and cooled them, he shaped 

 them with a knife into slender strips of about three lines in 

 size, and pierced at one extremity. An iron wire-passed 

 into this hole ; and one of the wires leading from the char- 

 coal thus prepared communicated with the positive pole, 

 the other with the negative pole of a strong pile." Tht 

 charcoal was more than half immersed in the water of a 

 separate tube. The tubes were closed below wftfe'pach' 



ment, 



