APPENDIX. 879 



Dr. Kane says that " ice formed at a temperature of 30° Fahren- 

 heit will yield a perfectly pure and potable element." Lieutenant 

 Weyprecht says, that they found ice of a " certain thickness " to yield 

 a pure water. Dr. Kane's statement and the opinions he expressed, 

 are to the effect that the colder the temperature of the air at the time 

 the ice is formed, the less salt will be contained in the ice. Dr. Saun- 

 derland of Parry's, and Dr. Walker of McClintock's expedition, ex- 

 press directly contrary views, and my experience leads me to coincide 

 with them. . . . (Tabulated Experiments.) This is simply one of a 

 number of instances which I think prove the fallacy of Dr. Kane's 

 opinion that the colder the temperature the purer sea ice. ... As 

 to an absolutely pure ice being formed at a temperature of — 30° 

 Fahrenheit, I am fully convinced to the contrary, as I have been able 

 to examine ice formed at various temperatures from -j- 28.5° Fahren- 

 heit to — 50° Fahrenheit, and have failed to find any sea water ice 

 absolutely free from salt. I have equally failed to find the statement 

 of Lieutenant Weyprecht borne out by my experience. It is true that 

 in thick ice you will find less salt in the deeper strata than in the upper, 

 but this is due in a great measure to the fact that the freezing process 

 necessarily goes on more slowly, as the upper strata of ice already 

 formed is a poor conductor. 



It may be that I have not had the opportunity of examining ice of 

 the required thickness (Lieutenant Weyprecht does not state how 

 thick), but from my present experience I should expect to find salt in 

 any specimen of sea water ice from wherever obtained. 



The following tabulated lists showing the result in a number of 

 experiments noted at the time, and the conditions under which the ice 

 was obtained, are not intended for comparison with each other, except 

 in cases marked, but simply to show the result in the given case. For 

 instance, in No. VIII. of the Table, ice formed at a temperature of 

 — 16.5° Fahrenheit, shows a much smaller amount of salt than a. of 

 No. IX. Here the conditions under which they were frozen come 

 into consideration. No. VIII. was taken from " Fire Hole " or sur- 

 face of the sea, where there was a more or less free movement of the 

 water, whereas No. IX. was frozen in a bucket, or rather tub, of a 

 slightly conical shape (which is an important factor). And also a cer- 

 tain amount of efflorescence had taken place from No. VIIL, and not 

 from No. IX. To compare the results obtained from any two speci- 

 mens you should know precisely all the conditions under which the ice 

 was formed. In the two specimens given in No. IX. {a., b.), I took 

 equal quantities of water obtained at the same time and exposed for the 



