482 M. Fromme on the Changes produced in the Molecular 



between two observations, giving a relative maximum or 

 minimum. Table III. A contains the results of this calculation 

 for the bar (d), as well as the mean density of the layers 

 dissolved off up to the observation in question, and the mean 

 density of the portion left. 



Table III. a. 



Number of 

 observation. 



8 V 



Density of 



layer removed 



between two 



observations. 



Density of the 

 portions removed 

 between the first 

 observation and 

 one of the subse- 

 quent ones. 



Density of the 



part of the bar 



unattacked. 



1 



4 



7 



13 



17 



20 



21 



26 



7-98 

 7-58 

 7-88 

 7-65 

 7-79 

 7-31 

 7-76 



7-98 

 7-76 

 7-82 

 7-75 

 9-79 

 7-74 

 . 7-74 



7-71 



7-72 

 7'70 

 7-71 

 7-70 

 7-72 

 7-71 



The values of 8 : show that there are layers of greater and 

 smaller density, alternating with each other ; those of B 2 taken 

 together with those of 8 3 show that the density decreases from 

 the outside towards the centre, since the density of the part 

 dissolved away always exceeds that of the remaining portion. 



The slowly cooled bar (e) was examined to see if the alter- 

 nating layers of denser and less dense metal were produced 

 by the sudden cooling. 



Table III. b* relates to the rod (e)\ h u 8 2 > $3 have the same 

 signification as in Table III A. 



Table III. b. 



Number of 



8 V 



fe 



d 3 . 



observation. 



1 



3 



7-93 



7-93 



7-79 



7 



7-70 



7-77 



7-80 



11 



7-89 



7-82 



7-78 



17 



7-75 



7-79 



7-78 



20 



7-64 



7-76 



7-79 



23 



7-92 



7-79 



7-78 



We find, then, the slowly cooled bar possesses exactly 

 similar variations in density as that eooled quickly in cold 



