336 Sir R. I. Murchison 07i the Silurian Rocks qfCortwoalU 



muriatic acid, and passing the voltaic current through it as 

 before, chlorate of potash was nevertheless formed, which was 

 subsequently converted into perchlorate of potash. 



The transformation of oxy-acids of chlorine, such as liquid 

 hypochloric acid (CIO4), or of a solution of chlorate of potash, 

 into perchloric acid by means of voltaic action, has been men- 

 tioned by Berzelius. I have ascertained, moreover, that when 

 a voltaic current is passed through hypochloric acid, espe- 

 cially when previously mixed with some sulphuric acid, free 

 chloric and perchloric acids are formed, after the disengage- 

 ment of a considerable quantity of chlorine. 



A concentrated solution of chloride of ammonium evolves 

 hydrogen at the negative pole but neither oxygen nor chlo- 

 rine at the positive pole. But the surface of the platina 

 plate representing the latter pole is covered with small yel- 

 lowish oily drops of chloride of nitrogen, which as soon as the 

 two poles are brought into contact decomposes with a more 

 or less violent explosion, chlorine and nitrogen being evolved. 

 This experiment illustrates at once the formation of this com- 

 pound and its highly explosive character. 



Cyanide of potassium if dissolved in water is easily oxidized 

 by a voltaic curi-ent, and converted into cyanate of potash, 

 but I did not succeed in obtaining a percyanate of potash. I 

 was not more successful in endeavouring to form a fluorate of 

 potash from the fluoride of potassium by the same means. 



I have not prosecuted my experiments further upon inor- 

 ganic substances, having from some observations on the be- 

 haviour of organic compounds under the action of the voltaic 

 curx'ent obtained results of so much greater interest, as to in- 

 duce me to give them my exclusive attention ; and at a future 

 time, when I have completed the investigation, 1 shall beg 

 leave to communicate it to the Chemical Society. 



LIII. On the Discovenj of Silurian Rocks in CormoalL By Sir 

 Roderick ImpeyMukchison, G.C. St. S.,F.R.S.,V.P.G.S. 



^ R, Geogr. S., Honorary Member of the Royal Geological 

 Society of Cornwall, Mem. Imp. Acad. Sc. St. Petersburg, Corr. 

 Roy. Inst. France, <Sfe. In a Letter addressed to Sir C. Lemon, 

 Bart., MP., President of the Royal Geological Society of 

 Cornwall. 



My DEAR Sir Charles, 

 J N compliance with the promise I made when attending your 

 -*■ last anniversary meeting at Penzance, I now give you a more 

 decided opinion than I was then enabled to do, respecting the 



