BLUE EARTH COUNTY. 449 



Hydraulic cement.] 



Adam Jefferson has burned two thousand to three thousand barrels of lime yearly since 1868. 

 The upper five to eight feet of the quarry worked by J. R. Beatty & Co., in Lime township, 

 are excellent for lime, of which they here burned 2,000 barrels yearly in 1878 and 1879. Joseph 

 Kunz, in the adjoining section 19. has also burned lime. 



Hydraulic ceriient is manufactured by the Standard Cement company, 

 on the east bank of the Blue Earth river about a mile southwest from the 

 west part of the city of Mankato. The discovery of the hydraulic quality 

 of the Shakopee limestone at this place is to be accredited to Mr. 

 J. R. Beatty. The cement is made from the regular layers of the Shako- 

 pee, the whole exposed thickness of the strata, amounting to about twenty- 

 two feet, being involved in the process. The rock varies somewhat from 

 top to bottom, being too siliceous in one part and too calcareous in an- 

 other, but when mingled in the process of manufacture makes a good hy- 

 draulic cement. Samples of the strata, selected for their excellence, have 

 been analyzed by Mr. C. F. Sideuer under the direction of Prof. Dodge, with 

 the following result:* 



No. 144. The powdered rock was digested in hydrochloric acid, whereby the greater part of 

 it was dissolved with effervescence due to the escape of carbonic acid gas. The composition of 

 the soluble and the insoluble portions is as follows: 



Soluble in hydrochloric and. 



Calcium carbonate, CaO CO; 40.00 



Magnesium carbonate. MgO CO* 31.50 



Ferric oxide, FeaOi 2.73 



Silica, SiO 2 traces 



Alumina, A1 2 O ., 0.85 



Potassa, K 2 O 0.22 



Soda. NajO 0.54 



75.84 

 Insoluble in hydrochloric acid. 



Silica 16.00 



Alumina 5.00 



Potassa traces 



Soda traces 



21.00 



Water 0.43 



97.27 



The soluble portion is seen to be mainly carbonate of lime and carbonate of magnesia, with 

 some oxide of iron, while the insoluble portion is silicate of alumina. 



The chemical characters of the manufactured cement have been de- 

 termined by Mr. Sidener as follows:* 



3v T o. 145. This material was found to effervesce very little witli hydrochloric acid, [t was 

 accordingly analyzed as a silicate, by fusion in the usual manner. The result of the analysis is 

 as follows: 



'Twelfth annual report. 



29 



