486 Adams <& CoJcer — Investigation into the Flow of Rocks. 



Original marble— 1st specimen. Specific 



gravity 

 Specific gravity after the rock had been placed in 

 water under a vacuum of 28j inches of mercury 



for 24 hours ... 2*722 



Original marble — 2d specimen. 



After treatment in a similar manner 2*722 



Average 2*722 



Deformed marble — specimen "A," 1st fragment. 



After having been placed in water under a vacuum 

 of 28 inches of mercury until no further air was 



given off 2*712 



Deformed marble — specimen "A," 2d fragment. 



Treated in vacuo in the same manner for 24 hours, 



no further air bubbles being given off 2*717 



Deformed marble — Specimen " B." 



After having been placed under water in vacuo for 



24 hours, until no further air was given off ._ 2*713 



Average 2*714 



The comparison thus stands : 



Original marble 2*722 



Marble after deformation 2*714 



Difference _. *008 



This may be taken to mean that the marble remains unchanged 

 in specific gravity by deformation, but that in the deformed 

 marble some of the little cracks or crevices developed in the 

 rock on relief of pressure still remain, into which the water 

 can not penetrate, and which give rise to the slightly lower 

 specific gravity of the deformed rock. In this connection it is to 

 be noted that specimen " A " could not be tested for strength on 

 account of the minute fissures by which it was traversed and 

 which were developed upon the relief of pressure incident to 

 the removal of the steel tube in which it was enclosed during 

 deformation, while specimen " B," which gave off compara- 

 tively few air bubbles, had the appearance of being much more 

 solid. 



In connection with these results it is interesting to note the 

 results of the investigations carried out by Spring* on the 

 specific gravity of the sharply folded limestones in the Alps. 

 In these he found that the specific gravity of the limestone on 

 the concave side of a sharp fold, where the pressure of course 

 is greatest, was slightly higher (*003 to *023) than on the con- 

 vex side of the same fold. This he at first interpreted as 



* Note sur la veritable origine de la difference des densites d'une couche 

 de calcaire dans les parties concaves et les parties convexes d'un meme pli ; 

 Ann. Soc. Geol. de Belgique, xl, p. 4, 1883-4. 



