A Study in the Natural History of Ice 291 



prosecuted with great zeal by the rising pioneers of modern 

 physical chemistry, and their labours furnished abundant 

 material confirmatory of the conclusions at which I had 

 arrived from my own experiments. The Zeitschrift fur 

 PJiysikalische C/iemie, which was founded at this date (1887), 

 is much occupied during the first eight or ten years of its 

 existence by reports of researches and speculations in this 

 field ; one result of which was that the amount by which the 

 freezing-point of water was lowered by the dissolution in it of 

 a minute proportion of a salt was claimed as a trustworthy 

 basis of arriving at the molecular weight of that salt. 



The purest water occurring in nature is at the best only 

 a dilute, but not an infinitely dilute, solution of foreign 

 ingredients. It would naturally be expected that physicists 

 and chemists who have made a study of land-ice since the 

 year 1887 would recognise not only the possibility but the 

 certainty that the ice and the water which they meet with on 

 glacier, neVe, or snow-field, must, under constant conditions 

 of pressure, melt and freeze at a temperature inferior to the 

 melting and freezing point of pure H 2 O. 



We search their writings on this subject in vain for any 

 recognition or application of this fundamental principle. 



Explanations which ignore an important law of nature 

 must be defective and may be misleading. 



The Source of the Impurity in the Intergranular Water. 



The principal source of the impurity in the water which 

 moistens the granular surfaces of ice, neve and snow is rock 

 debris, which may take the form of stones, sand, dust or mud; 

 and it is to be found everywhere, even in what is apparently 

 clear ice. 



This has often given me a great deal of trouble when 

 photographing the ice of the walls of the grotto. In summer, 

 when all the ice in the grotto is melting, its surface is con- 

 taminated with dirt, principally mud with some sand. When 

 the outer superficial layer of the ice melts, the water runs 

 away apparently quite clear, and the mud which has been 



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