198 FREEZING MERCURY. [January, 



weight ; it then recovered itself ; and finally, on being 

 re-weighed in my cabin, was deficient T75 grains. 



In order to determine its effect on water, I turned the 

 frozen mass into a tumbler of water containing six fluid 

 ounces at 47 '5: the mercury simply became encased 

 in ice, and when it at length flowed on the bottom, the 

 temperature indicated 44 '5, a difference only of 3. I 

 was anxious to determine the form of its crystal : this 

 was a very difficult matter. It was attended with great 

 inconvenience in the open air, and the change was 

 screened by the superficial crust forming before the body 

 became solidified. The transition from the solid to fluid 

 could be better watched : this I tried. It then occurred 

 to me that by using a large open-mouthed jar, contain- 

 ing half a gallon of spirit of wine or alcohol cooled down 

 to 47 '5, that I could leisurely, in my cabin (aided 

 only by caudle-light), watch its motions, and freeze or 

 liquefy at pleasure. In this I succeeded, remarking 

 however that several travelling mercurial and other 

 thermometers presumed to read below 42 ! But to the 

 result of my examination : previous to freezing, or at the 

 instant of returning to fluidity, I noticed that the mer- 

 cury assumed a very active motion, resembling living 

 polypi, parts moving in circles with great velocity. 

 Positive crystallization I could not detect, but the in- 

 clination appeared to be nearer to the forms of lead 

 or bismuth on cooling, the surface lines being clearly 

 rectangular, or a beautiful network. This was on the 

 semifluid ; in its dense form nothing could be traced. 

 Although much exposed today to low temperature, no 

 change in my ordinary cabin dress was found requisite, 



