THE LINEAR FORCE OF GROWING CRYSTALS 



3 2 3 



temperature, rate of evaporation, and load. It is also possible that 

 steps 2 and 3 in this process may have a different order from that 

 assumed. This is, however, of small consequence here. The prin- 

 ciple to be recognized is that potential supersaturation will be 

 reached in the liquid layer adjacent to the unloaded crystal first, 

 and in the layer adjacent to the loaded crystal later, if at all. If 

 no supersaturation occured, obviously no growth of the loaded 

 crystal would be possible. Growth at the bottom of the loaded 

 crystal may therefore be positive, zero, or negative, and is much 

 more likely to be zero or negative than positive in the conditions 

 described by Bruhns and Mecklenburg. The rate of evaporation 

 and the amount of the load are governing conditions here, suppos- 

 ing always that no other nuclei develop. 



Two sets of measurements are submitted in support of this 

 analysis. Table IV contains the record of two crystals, a loaded 

 (74 gm.) and an unloaded one, placed in a saturated solution 

 together, after the manner of Bruhns and Mecklenburg, and the 

 results confirm their observations (Table II) perfectly. The 

 unloaded crystal grows at the top, sides, and in the supporting rim 

 below, while the loaded crystal shows no growth in the direction 

 of the load. 



TABLE IV 



Conditions as Before 



The results of Table V may perhaps serve to illustrate wherein 

 Bruhns and Mecklenburg were hasty in generalizing from such an 

 observation to the sweeping conclusion that no growth can take 

 place in a loaded crystal in the direction in which the load is applied. 

 This experiment (Table V) also shows two crystals, a loaded and 

 an unloaded one, in the same saturated solution, and differs in no 

 detail from the previous case (Table IV) save that the load has been 



