172 Scientific Proceedings, Royal Dublin Society. 



Mr. McKee's work is divided into four sections, as follow : — 



1. Eepetition of Beyerink and Van Delden's work on the reduction of 



sulphates by two distinct species of micro-organisms present in 

 fresh and salt water respectively, namely, Microspira desulphuricans 

 and M. estioarii. 



2. The action of carbon dioxide on ferrous sulphide suspended in water. 



3. Evolution of hydrogen sulphide from foul mud kept in contact with a 



saturated solution of carbon dioxide, and 



4. Sulphuretted hydrogen production from putrefying green sea-weeds. 



At the end of the paper, the mechanism of the reactions is discussed 

 whereby the sulphates originally present in sea-water give rise to ferrous 

 sulphide and eventually to hydrogen sulphide and ferrous carbonate, by the 

 action of carbon dioxide on ferrous sulphide, thus: — 



f M' 2 S0 4 Organic matter and f M' 2 S 

 (A). Seawater^ + =1 + CO, + 2H,0 + 2NH, 



t_M"S0 4 M. Estuarii \M."$ 



'M',S ( 2M'(HC0 3 ) 



+ 2C0 2 + 2H 2 = + H 2 S 



W\S ( M"(HC0 3 ) 2 



Fermenting matter < 2FeO 

 + = +H 2 



(= Reducing agent) ( 2Fe(OH 2 



FeS + H 2 

 (D). H 2 S + 



' Fe(OH) 2 ( FeS + 2H 2 



Excess 



(E). FeS + 2C0 2 + 2H 2 ^=z^ Fe(HC0 3 ) 2 + H 2 S 



Where M! is a metal of the alkalies, e.g. sodium, and M" an alkaline earth 

 metal, e.g. calcium. 



The question next arose, how will carbon dioxide act on certain sulphides, 

 namely, the four mentioned above {i.e. those of iron, calcium, magnesium, 

 and sodium), and, conversely, how will hydrogen sulphide act on the carbonates 

 of the same metals ? 



Action of Carbon Dioxide on Sodium Sulphide. 



The first experiments were tried with sodium sulphide. A current of 

 carbon dioxide being passed into a solution of that salt, when abundance of 



