1852.] AMOUNT OF EVAPORATION. 177 



grains ; re-weighed before exposure on the lower deck 

 0^ drachms : in three hours it had absorbed 38 grains ; 

 in five hours, 36, given up 2 grains ; after hanging in 

 my cabin twelve hours it had lost 8 grains. I fully 

 intended subjecting this precious morceau to freezing 

 proofs, but bad weather prevented this cruelty. 



I do not think that any of the other processes carried 

 on at this period, except the freezing of water in glass 

 cylinders, are likely to interest others than those for 

 whom they were expressly made, and which may possibly 

 be placed in the Appendix. 



Excepting Scoresby, few, I believe, have enjoyed the 

 study of the forms of ice-crystals. I have ever felt deep 

 interest in crystallography, as regards minerals, and mi- 

 neral and other salts ; therefore I could not but feel cu- 

 rious in watching the slow process of freezing. A very 

 clean glass cylinder, about a foot in length and one inch 

 internal diameter, filled with clear water at 50, was 

 submitted to a temperature of 24: the vapour con- 

 tinued to flow off for a considerable time after the water 

 was frozen, and the ice had elongated itself out of the 

 tube (which was very strong). 



During the process of freezing (as we may often ob- 

 serve in the crystallization of salts), I had the tube 

 placed in the focus of a strong reflecting carriage-lamp, 

 and was thus able to trace, on a white ground behind, 

 the beautiful regularity of its every motion, from the first 

 silvery thread to the total condensation. 



I noticed that the crystallization commenced from be- 

 low, and shooting its feather-like processes, signalizing as 

 it were (with its arms at 60 above or 120 below) to the 



VOL. I. 



