152 



with the sulphur of the sulphate, while the soda in presence of 

 carbonate of lime and carbonic acid is eliminated as a sesqui- 

 or bicarbonate, of soda. 



Below St. Louis, the turbid water of the Mississippi contains, 

 as its characteristic salt, the bicarbonate of soda ; and its sus- 

 pended matter being deposited by rest, we always find in the 

 clear water this alkaline salt, constituting a large part of the whole 

 saline matter. I have been able to trace the steps of the pro- 

 duction of the bicarbonate of soda from the sulphate of soda, by 

 the silt of this river in my vessels. The sulphide of iron, also 

 produced at the same time, oxidizes in free air, becoming oxide 

 of iron and free sulphur. Sulphates are not the final result of the 

 oxidation of basic sulphides usually. The clay-colored cliffs and 

 banks of the Mississippi exhibit the oxidized state of the small 

 portion of iron oxide, one of its constituents, while the dark, and 

 even black, color of the buried mass beneath the surface, is due 

 to the reduced, and generally sulphuretted, state of the iron ; a 

 condition caused by the changing organic matter. Until the dis- 

 covery of the existence of sulphate of soda in the soil washed by 

 the tributaries of the Mississippi, its origin in the water was a 

 subject of doubt, and in this connection the new fact becomes 

 important. 



Regarding the immense body of water discharged by the 

 Mississippi, as a diluted solution of bicarbonate of soda, which 

 falls into a warm ocean containing lime salts, easily decomposed 

 by the soda salts, we have chemical action on an extended scale. 

 The result of this action must be some form or forms of carbon- 

 ate of lime, fitted either for the habitations of shell-building fish, 

 or for consolidating calcareous rocks. 



Returning to the first exhibition of chemical change, we see the 

 influence of the minute quantity of organic matter, dissolved in 

 the water — a constituent so small in weight that it has been 

 generally neglected in the analysis of waters — and yet, under 

 favorable circumstances, becoming a sufficient cause in bound- 

 ing a coast line with cliffs, or even producing a rock formation. 



Prof. William B. Rogers remarked upon the interesting bear- 

 ings of the communication read by Dr. Hayes. The fact of 

 the entire deoxidation of sulphuric acid, on the great scale in 



