REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1903 131 



Physical properties of gypsum. Sufficient has already been said 

 about most of the physical properties of gypsum [p. 91 et seq.], 

 but the results of recent experiments render it necessary to go 

 more deeply into the subject of the solubility of gypsum. 



A table has already been given showing the results obtained 

 by Marignac, and, for the average reader as well as the author, 

 it will seem more practical than the more recent table which 

 has been prepared to show the number of millimolecules of 

 gypsum in a liter of a normally saturated solution. The results 

 of Poggiale, Marignac and Droez have been calculated to 

 millimolecules per liter. 











Normally saturated 











solutions 



Temp.i 



Poggiale 



Marignac 



Droez 



Hulett and Allen 



0° 



15.06 



14 





12.91 



5.5 









14.11 



13.56 



14.2 







14.83 



14.50 



18 





15.06 





14.81 



19.5 









15.66 



14.88 



20 



17.72 







14.95 



24 





15.30 



15.87 



15.23 



32 





15.64 





15.38 



35 



18.75 









15.40 



36 









16.19 



15.41 



38 





15.79 







15.41 



41 





15.71 







15.39 



53 





15.52 





14.85 



72 





14.86 





12.70 



86 . 





13.94 







12.70 



99 





12.89 





11.95 



100 









11.90 



Lavoisier discovered in his experiments that, on heating 

 gypsum, water was removed at two different stages, and further- 

 more that, while it was a simple matter to remove three quarters 

 of the water, it required more time and much higher tempera- 

 ture to force out the remaining quarter. 



In 1830 these results were confirmed by Payen, who found 

 that water commences to pass off at 115° C, and that the loss 



1 Hulett, George A. & Allen, Lucius E. 

 Am. Chem. Soc. July 1903. v. 24. 



The Solubility of Gypsum. Jour. 



