STATE GEOLOGIST. 163 



GYPSUM. 



So much has already been said of the geographical and geo- 

 logical position of the gypsum of our State, that I only add a 

 » few memoranda. 



The following analyses were performed, at my request, by 

 Prof. L. E. Pisk, of the Agricultural College: 



Grand Rapids 

 Gypsum. Ohio Gypsum. 



Water 20.8445 20.8631 



Silicic acid Trace. . 0235 



Alumina and Oxyd of Iron 5854 . 7626 



Sulphuric acid, 46.2257 45.8303 



Lime 32 . 03-5 31 . 5628 



Potassa, 2115 .2676 



Soda .0140 .0944 



Chloiiue, 0078 .0050 



Total 99.8774 99.4093 



The above statement does not exhibit at a gla,nce, the com- 

 parative purity of the two products; we therefore calculate the 

 following further results: 



Grand Rapids. Ohio. 



Lime, as above 32 . 0385 31. 5628 



Sulphuric acid required for this, 45 . 7696 45 . 0897 



Water required for these two 20 . 5962 20 . 2903 



Total hydrous gypsum 9ti.4u43 96.y4^8 



Excess of sulphuric acid,. 4561 .7406 



Excess of water, 2483 .5728 



Other constituents, 7687 1.1531 



Total as before, 99.8774 99.4093 



It thus appears that the sample of Grand Rapids gypsum 

 analyzed, contained only 1.5957 parts in 100, of impurities, 

 and the Ohio gypsum only 3.0.372. Of these impurities, how- 

 ever, the sulphuric acid, potash and soda, are at least equally 

 valuable with pure gypsum. These ingredients amount to 

 .6816 in the Grand Rapids sample, and 1.1026 in the Ohio 

 sample, leaving for the residual, worthless constituents of the 

 former .9141 per cent, and of the latter 1.9546 per cent. 



