Beport of the Researches of if. Agassiz* 296 



occurs only in the lower regions of its descent. The ice of 

 the gallery afforded us an example of this transformation ; for 

 here we could but imperfectly distinguish between the white 

 and the blue ice, and the liquid everywhere infiltrated with 

 the same rapidity. We have found that the chromate of 

 potash is preferable, for these experiments, to the infusion 

 of logwood, however strong it may be ; the chromate, more- 

 over, is of infinitely easier carriage, and dyes more deeply, 

 especially when mixed with a little acetate of lead. With a 

 quart of this solution we have coloured a considerable stream 

 to the extent of many hundred feet. 



From these experiments, it follows, that water transudes 

 through ice throughout the whole extent of the glacier ; that 

 this transudation takes place in different ways, and with a 

 velocity varying in different places ; that ;in the neve the 

 transudation is uniform in its progress ; that in glacier ice, 

 properly so called, it is effected by means of a net-work of ca- 

 pillary fissures, which extend as far as we can penetrate, and 

 probably throughout the entire mass ; and, finally, that in the 

 middle region of the glacier, in which the differences between 

 the white ice and the blue, which may be called the ice of in- 

 filtration, are still marked, the transudation occurs much more 

 rapidly in this latter than in the former ; and in proportion as 

 these differences are lost, the infiltration takes place in a uni- 

 form manner. 



These results are fully confirmed by the following observa- 

 tions. When we remark, after a cold night, the different hol- 

 lows full of water, and which exist in great numbers at the 

 surface of the glacier, we usually find the surface of the water 

 covered with a pellicle of ice, which disappears as the day 

 advances. In the morning this pellicle does not repose imme- 

 diately upon the water, but is separated by a space, which 

 varies from half an inch to two inches, and even more. It 

 begins to form immediately after sunset ; and often we see 

 spiculae of ice on the surface of the pools as early as six 

 o'clock. The ice thus protecting the water against evapora- 

 tion, there remains but one means of explaining the diurnal 

 lowering of its surface, namely, the admitting the infiltration 

 into the interior. The same consequence results from the 



