Faraday on the Vapour of Mercury^ &c. 365 



ments above mentioned, been removed. A small portion of 

 mercury was put through a funnel into a clean dry bottle, ca- 

 pable of holding about six ounces, and formed a stratum at the 

 bottom not one-eighth of an inch in thickness ; particular care 

 was taken that none of the mercury should adhere to the upper 

 part of the inside of the bottle. A small piece of leaf-gold was 

 then attached to the under part of the stopper of the bottle, so 

 that when the stopper was put into its place, the leaf-gold was 

 enclosed in the bottle. It was then set aside in a saf^ place, 

 which happened to be both dark and cool, and left for between 

 six weeks and two months. At the end of that time it was 

 examined, and the leaf-gold was found whitened by a quantity 

 of mercury, though every part of the bottle and mercury re- 

 mained apparently just as before. 



This experiment has been repeated several times, and always 

 with success. The utmost care was taken that mercury should 

 not get to the gold, except by passing through the atmosphere 

 of the bottle. I think, therefore, it proves that at common 

 temperatures, and even when the air is present, mercury is 

 always surrounded by an atmosphere of the same substance. 



Art. XIII. Some Account of the late Expedition to the 

 Polar Regions, under the Command of C^n^tam William 

 Edward Parry. 



The circumstances attendant on the failure of the search for 

 a north-west passage, by the expedition under the command of 

 Captain Ross, in the year 1818, induced the Lords of the Ad- 

 miralty to make another experiment ; and accordingly the Hecla 

 and the Griper, properly fitted out for the undertaking, were 

 placed under the command of Lieutenant Parry ; a gentleman, 

 who, as the result has amply proved, was highly qualified for 

 an undertaking, perilous in itself, and rendered peculiarly ardu- 

 ous by the failure of his predecessor. 



This expedition left the river in the month of May, 1819, 

 and arrived, on the 14th of June, off Cape Farewell, which is 



