264 SUMMARY OF RESULTS. 



It is conceivable that the conditions (a), (6), (c), and (d) should lead to 

 a primary deposit of exceptionally pure gypsum, especially when acting 

 jointly. The considerations developed make it desirable to examine such 

 and other deposits of gypsum very carefully and exactly for even very 

 small quantities of carbonate. 



(7) Even if the great mass of an excess of calcium carbonate in a solu- 

 tion were deposited first in some other locality before the point of satura- 

 tion for gypsum were reached, the requirements for equilibrium would be 

 such as to hold carbonate in solution and to make the question of the place 

 of deposit of the excess of carbonate in the first instance one of no moment. 



