644 PROCEEDINGS OF THE XEW YORK MEETING 



Eemarks were made by J. F. Kemp and A. C. Lane. 



The following- paper was then read by title : 



OCCURRENCE OF UNUSUALLY LARGE CALOITE CRTSTALS IN NE^7 YORK 



STATE 



BY I). H. XF.WLAiVD 



The next jDaper was 



ASYMMETRIC DIFFERENTIATION IN A BATHYLITH OF ADIRONDACK SYENITE 



BY H. P. CUSHI^'G 



The paper a^'rs discussed by A. C. Lane. It forms pages 477-492 of 

 this volume. 



The following ^japer was then read by title : 



FORMATION OF LEUCITE IN IGNEOUS ROCKS 

 BY HETv'EY S. WASHINGTOjV 



The next paper was 



GENETIC RELATIONS OF SOME GRANITIC DIKES 

 BY ALFRED C. LANE 



Contents 



Page 



1. Effect of difference of conditions on crystallization 644 



2. Application to pegmatites G4."> 



3. Observations in the Huron mountains 64.5 



4. Conclusions 647 



I. Effect of Difference of Conditions on Crystallization 



One of the fimdauieiital priuciiiles in c-ousiclering the coarseness of fcraiii 

 of rocks is that, other things being equal, the less the difference between the 

 conditions before and after crystallization, the coarser will be the crystalliza- 

 tion. Wlien the difference of conditions is small, the rate of change from the 

 one state to the other will also be slow, and the crystallization proportion- 

 ately coarse. We note this in the laboratory, where the coarse crystals are 

 formed from the felatively cool or tepid solutions, and in the kitchen.- where 

 the conditions for making the coarsely crystallized rock candy are sharply 

 contiasted with rapid cooling and stirring of a hot syrup rerpiired to make a 

 "fondaut," which forms the center of chocolate creams. This principle is one 

 of the first consequences of the proposition that the grain is proportional to 

 the slowness of cooling.* 



♦Annual Itoport Geological Survey of Michigan, 1903, p. 212. 



