190:>.] Solids under Mechanical Disturbance. 219 



The experiment was made by filing a flat surface on the antimony 

 with a very fine watchmaker's file. Even with this smooth file the 

 surface of the antimony was a good deal broken into crystalline ridges 

 and hollows by the splintering of the brittle metal. After as flat a 

 face had been obtained as was possible with this tool, it was rubbed, 

 still in the direction of the file marks, on the finest emery paper 

 (No. 00 French) till the file marks had disappeared, only the deeper 

 pits and hollows remaining. Fig. 2 shows the surface at this stage, 

 from which it is seen that the general character of the ridges and 

 furrows left by the emery is smooth and rounded and that the smaller 

 pits, which had resulted from the breaking out of crystalline chips, are 

 in many cases losing their angularity and assuming a rounded form. 

 The specimen was next rubbed across the line of the emery scratches on 

 a polishing block covered with washleather sprinkled with the finest 

 rouge. Fig. 3 shows the surface at this stage. The polishing has 

 spread the metal across the ridges left by the emery like a viscous 

 paste, sometimes filling the furrows and sometimes bridging them over. 

 In some cases the line of the furrow can only be traced by the row of 

 holes in the covering film. The circular form and the smooth rounded 

 edges of the holes are quite consistent with the other appearances of 

 viscous flow. 



A part of the surface was now etched with a solution of potassium 

 cyanide. Fig. 4 shows the effect of the solvent in removing the layer 

 which has been spread over the surface by the polishing. The portion 

 of the original photograph, which is reproduced here, shows on the 

 left side the effect of the removal of the surface, and on the right a 

 portion which was protected from the action of the solvent by varnish. 

 The removal of the surface layer has again uncovered the furrows and 

 ridges left by the emery, and the impression conveyed by the preceding 

 photograph (fig. 3) is confirmed, namely, that the ridges and furrows 

 had been covered over, not levelled down or removed. It is further 

 seen that the understructure of the ridges is rough and crystalline, 

 the appearance of the flow given by the polishing having been only 

 skin deep. 



In examining the specimen under the microscope the attention was 

 arrested by the curious appearance presented by two of the pits on the 

 surface, which appeared as if covered over with a film of greatly 

 diminished reflecting power as compared with the rest of the surface. 

 A search over other parts of the surface disclosed a number of similar 

 pits which showed the covering film with greater distinctness. A group 

 of these pits is shown on fig. 5 ; in these the solvent has acted on the 

 film less than it has on the covering of the pit seen in fig. 4, and the 

 continuation of the surface markings can be traced across the film over 

 the pit. 



On another part of the surface which had not been exposed to the 



