Curiosities of Science. 161 



and quite calm, is infinitely preferable to fifteen below, or 

 thereabout, with a strong breeze of wind. Spirit of wine is, 

 of course, the only thing that can be used in the thermometer ; 

 as mercury, were it exposed to such cold, would remain frozen 

 nearly half the winter. Spirit never froze in any cold ever 

 experienced at York Factory, unless when very much adulter- 

 ated with water ; and even then the spirit would remain liquid 

 in the centre of the mass. Quicksilver easily freezes in this 

 climate, and it has frequently been run into a bullet-mould, 

 exposed to the cold air till frozen, and in this state rammed 

 down a gun-barrel, and fired through a thick plank. The 

 average cold may be set down at about 15 or 16 below zero, 

 or 48 J of frost. The houses at the Bay are built of wood, with 

 double windows and doors. They are heated by large iron 

 stoves, fed with wood ; yet so intense is the cold, that when 

 a stove has been in places red-hot, a basin of water in the room 

 has been frozen solid. 



PURITY OF WENHAM-LAKE ICE. 



Professor Faraday attributes the purity of Wenham-Lake 

 Ice to its being free from air- bubbles and from salts. The 

 presence of the first makes it extremely difficult to succeed in 

 making a lens of English ice which will concentrate the solar 

 rays, and readily fire gunpowder ; whereas nothing is easier 

 than to perform this singular feat of igniting a combustible, 

 body by aid of a frozen mass if Wenham-Lake ice be employed. 

 The absence of salts conduces greatly to the permanence of the 

 ice ; for where water is so frozen that the salts expelled are 

 still contained in air-cavities and cracks, or form thin films 

 between the layers of ice, these entangled salts cause the ice to 

 melt at a lower temperature than 32 J , and the liquefied por- 

 tions give rise to streams and currents within the body of the 

 ice which rapidly carry heat to the interior. The mass then 

 goes on thawing within as well as without, and at tempera- 

 tures below 32 ; whereas pure, compact, Wenham-Lake ice 

 can only thaw at 32, and only on the outside of the mass. 

 Sir Charles LyeWs Second Visit to the United States. 



ARCTIC TEMPERATURES. 



Dr. Kane, in his Second Arctic Expedition, found the ther- 

 mometers beginning to show unexampled temperature : they 

 ranged from 60 to 70 below zero, and upon the taffrail of the 

 brig 65. The reduced mean of the best spirit-standards gave 

 67 or 99 below the freezing point of water. At these tem- 

 peratures chloric ether became solid, and chloroform exhibited 

 a granular pellicle on its surface. Spirit of naphtha froze at 54, 

 and the oil of turpentine was solid at 63 and 65. 



M 



