332 PROCEEDINGS OF THE ACADEMY OF [1880. 



100.94 



This result may be estimated as a confirmation of Richter's 

 analysis, which gave to Jarosite the formiila of " alunite,'' with 

 which it is isomorphous. 



Thus 41unite = K^AlgS.O,, + 6A.,0 

 Jarosite = K^FceSiO,, + 6H,,0 



The utmost care was given to the estimation of the alkalies, the 

 sulphuric acid and the water, as the question of constitution must 

 be dependent mainly upon them. 



August 10, 



The President^ Dr. Ruschenberger, in the chair. 

 Sixteen persons present. 



August IT. 



The President, Dr. Ruschenberger, in the chair. 



Twelve persons present. 



A paper entitled " Rhizopods in the Mosses of the Summit of 

 Roan Mountain N. C," by Jos. Leid}^, M. D. was presented for 

 publication. 



August 31. 



The President, Dr. Ruschenberger, in the chair. 

 Fourteen persons present. 

 The following was- ordered to be printed : 



