350 



PROCEEDINGS OF Till-: AMERICAN ACADEMY. 



These data are plotted in Figure 16. 



l 2 

 Time from birth of crystal 



Figure 16. Diagram Representing Rate <»k Increase in Crystal 



1 >i \ mi ri:i:. 



] represents point from average of crystal* taken at random. 

 O represents point from average <>f selected crj Btals 



represents probable actual rate of growth. 



represents equation I >'• let. 



represents equation /'■' - kt. 



The unit of time is the time of one revolution of the Bhutter, or 1 ,25 Beconds. 

 The Bubstance w m - potassic iodide. 



The inspection of the figure shows al once thai the curve is similar in 

 eral shape to one represented l»v the equation P" li. where l> h 



