586 Mr. Mallet on the Brittleness and 



We could not succeed in obtaining aniline by passing the 

 vapour of nitrobenzoene through a heated tube, finding that 

 when the temperature is not very high, the oil distils over 

 unchanged, while, if the heat is great, the whole is consumed, 

 forming a dense brownish-black cloud. We recognised, 

 nevertheless, the formation of aniline in an unquestionable 

 manner, by distilling nitrobenzoene with an alcoholic solution 

 of potash, in order to procure the substance corresponding to 

 Mitscherlich's azobenzide, for on adding hypochlorite of lime 

 to the distillate which contained the red crystals of azoben- 

 zo^ne (?)j a beautiful purple reaction ensued. 



The formation of aniline in this manner affords, perhaps, 

 a new mode for obtaining bodies possessing basic properties, 

 which we intend studying in conjunction with the products of 

 decomposition of nitrohenzide and a few other analogous com- 

 pounds. 



LXXXIV. On the Brittleness and Non-plasticitij of Glacier 

 Ice. By Robert Mallet, Esq., M.R.LA.^ 



1 N the course of the discussion upon the mechanics and con- 

 ^ ditions of motion of glaciers, which has continued since 

 the publication of Prof. Forbes's first papers on the subject, 

 very much stress has been laid by most authors, and espe- 

 cially by Prof. Forbes himself, on what he has called the 

 plasticity of the glacier ice. Indeed, so important a part does 

 this assumed property play in his views, that he almost appears 

 to rest his claims to discovery, or at least to enunciate his 

 discovery of the nature of glacier motions, in the assertion of 

 this plasticity of mass. A great deal of ink has been wasted 

 in controversy respecting this assumed property, from the 

 want of forming distinct ideas as to what this quality in ques- 

 tion really is; and, having fixed its conditions, determining 

 whether such were compatible with the known properties of 

 ice. Nor have the verbal definitions of Dr. Whewell recently 

 published in the Philosophical Magazine at all helped the 

 matter. 



It is not my present object to enter upon the question of 

 glacier motion generally. I have for some years abstained 

 from joining in the controversy which I was the first British 

 author to raise, confident that ultimately the views I origi- 

 nally promulgated as to the great motion of translation of 

 glaciers would be acknowledged true ; and having already 

 seen one opposing theory (that of Charpentier and Agassiz) 

 consigned to merited oblivion, after having carried away the 



* Communicated by the Author, having been read before the Geological 

 Society of Dublin. 



