322 GEORGE F. BECKER AND ARTHUR L. DAY 



this crystal lifted its load (Table III), and we are concerned at the 

 moment less with the form than with the fact of linear growth in 

 the direction of the load. Bruhns and Mecklenburg have recog- 

 nized and pictured this peripheral rim (Wulsi) and admit its 

 lifting action for increasing loads of crystal substance, 1 but 

 deny lifting power when crystal substance is replaced by foreign 

 substance. 



The distribution of growth about an unloaded crystal is rather 

 well shown by the same device. Fig. 3 is a vertical section through 

 an unloaded crystal of potash alum grown in a solution saturated 



with both chrome and potash 

 alum. The color plainly reveals 

 the distribution of new crystal 

 substance and shows the origi- 

 nal crystal, together with the 

 mass of new matter deposited 

 upon its upper surface, to have 



Fig. 3. — Distribution of new growth . . 



about an unloaded crystal been llfted bodl l v O. 4 mm. by 



the new growth. It may be 

 noted also that the original crystal was inverted from its position 

 of original growth (its cup is still distinguishable facing upward) 

 in order that subsequent growth might suffer no modification 

 through special limitations of circulation imposed by the original 

 supporting rim. 



By the same reasoning, the case offered by Bruhns and Mecklen- 

 burg (Table II) is capable of equally definite analysis. Here we 

 have in the same solution two crystals, one loaded and the other 

 not. The saturation concentration will ordinarily be first reached 

 upon the top and side surfaces of the unloaded crystal; secondly, 

 in the exposed (and strained) side surfaces of the loaded crystal; 

 thirdly, in the supporting liquid layer beneath the unloaded crys- 

 tal; and last of all, in the liquid layer beneath the loaded crystal. 

 Whether this last concentration can be reached in the presence of 

 the three lower saturation concentrations, all of which are exacting 

 their toll of the solution, will depend upon fortuitous relations of 



'See Bruhns and Mecklenburg's paper, p. 105; also the quotations therefrom, 

 footnote, p. 320. 



