4 RECORD AND DISCUSSION OP TEMPERATURES. 



In order to test his thermometers, Dr. Kane provided himself with chemically 

 pure mercury, and noted the temperatures at Avhich it became solid. The follow- 

 ing notes have been extracted from the log : — 



Nov. 25, 1853. The mercury was exposed upon the floe at the meteorological observatory, and remained 

 liquid with the spirit standard at — 42°.0. 



Dec. 8, 1853. At two o'clock, the mercury exposed was found frozen at — 40°. 5 of the spirit standard, 

 the mercurial standard being at — 3 9°. 8. 



Dec. 14, 1853. The mercury froze around the edges of the saucer containing it; S at — 41°. 0, and 31 

 at — 40°.0. 



Jan. 16, 1854. Mercury in bulb ceased to record at — 43°. 5 ; observed frozen at — 38°. 0. 



Jan. 29, 1854. The mercury in the standard instrument, after registering — 43°. 0, descended in the 

 bulb; at another time it registered, after being frozen, — 44°. 0, and then became sta- 

 tionary. 



Nov. 29, 1854. Mercury congealed at — 43°. of spirit standard, and resumed its fluidity at — 38°. 0. 



If we refer the readings of the spirit standard to those of the mercurial standard 

 by adding +0°.3, we obtain the following observed temperatures for the freezing 

 point of mercury : — 



-40°.2 



-39°.8 



-40°.7 



— 40°.0 



-38°.0 



and — 42°.1 Mean, —40°. 2 



Similar differences in the freezing point of mercury have been noticed by other 

 observers; Parry, for instance, saw the mercury liquid at — 43°. The above mean 

 being so near to what is generally assumed ( — 40°) as the point of congelation, I 

 thought it best to apply no correction to the readings of the mercurial standard, 

 and to diminish that of the spirit standard, for temperatures lower than — 40°, by 

 the apparent difference, at that temperature, between the indications of the mer- 

 curial and all other thermometers compared with it, or by the constant 1°.5 ; thus 

 the maximum correction to the spirit standard becomes — 6°.0 at — 60°. 



Thus applying the proper corrections to the spirit standard S, according to ob- 

 servations of February 4, 1854, spirit of naphtha became solid at — 57°, oil of sassa- 

 fras at — 46°, bisulphuret of carbon at — 26°; oilof wintergreen clouded at — 40°, and 

 remained liquid at the maximum temperature of that day, viz : — 63° ; the ethers 

 likewise remained unchanged. On the following day, aqua ammonia F. F. froze 

 solid from two hours exposure at a temperature of — 52°, chloric ether became solid, 

 and, after four hours of exposure, chloroform was covered with a granular follicle 

 at —66°. 



