A CONTRIBUTION TO THE STUDY OF ICE-STRUCTURES 



Qualitative tests carried out at the Hut, testing the ice chemically at intervals 

 between the surface and the residual brine, showed the surface fifteen inches to be 

 almost pure water. Below fifteen inches the saline contents rapidly increased. This 

 is well illustrated in the column of densities below. 



The following is a table of specific gravity determinations, by the Buchanan Hydro- 

 meter, of waters resulting from melting samples of the ice taken at intervals in the July 

 shaft. The second column represents determinations of the temperature of commence- 

 ment of freezing of the thaw-waters. 



The liquid brine from the June shaft between five feet six inches and six feet had a 

 specific gravity of 1T42 at the same temperature; commencement of freezing 22° F. 

 A sample of the ice from the very bottom, five feet three inches to five feet six inches, of 

 the July shaft was taken to the Hut with others and left in the outer laboratory pending 

 examination. Unfortunately it was contained merely in a bag, as was the usual procedure. 

 When examined it was found to have partially melted and run away, thus indicating 

 the exceedingly low freezing temperature of some of the cryohydrate contained in it. 



It is quite probable that, had the earlier shafts not been sunk, there would still 

 have been some liquid brine below the ice in July. As soon as the earlier shafts broke 

 through to the liquid the latter rushed up and rapidly froze as a uniform, somewhat 

 yellowish, enamel-like saline ice. 



Crystalline structures. The dominant structure was that of a vertical prismatic 

 arrangement ; such as is typical of liquids freezing from above. Each prism was seen 

 to extend in a vertical direction for several inches, some for quite a foot. Near the 

 surface, where the ice was freshest, cross-sections perpendicular to the long prism axis 

 showed the average diameter of the individuals to be about a quarter of an inch, whilst 

 the maximum diameter attained was found to be three-quarters of an inch. At a 

 depth, where the ice was more saline, the structure gradually changed. Upon a glance 



