THE PRODUCTION OF SULPHURETTED HYDROGEN 25 



The water at the sea bottom contained twenty times as 

 much hydrogen sulphide as the surface layers.* This seems 

 to indicate that the sulphide in the lower layers originates 

 from the sea bottom as a result of the active decomposition 

 of organic matter under anaerobic or micro-aerobic conditions, 

 for it would be difiticult otherwise to account for the presence 

 of the sulphide. 



The Limans. 



This name is given to the shallow salt marshes at the 

 mouths of the Dnieper which open into the Black Sea at 

 Odessa. The bed of these marshes is composed of black 

 mud which reeks of hydrogen sulphide, and is alkaline in 

 reaction. On exposure to air it turns a grey colour, but be- 

 comes black once more when covered with water. Anaerobic 

 bacteria liberating hydrogen sulphide have been isolated from 

 this mud, and one has been identified as the Vibrio hydro- 

 sulfureiis to which reference has already been made. It is 

 claimed that this organism is responsible for the reduction of 

 oxy-sulphur compounds to the substance which imparts the 

 black colour to the mud. This is a hydrate of sulphur and 

 iron, and forms a black colloidal covering to the other con- 

 stituents of the marsh bed. 



The Author's Investigation of the Black Sand of the 

 Clyde Estuary. 

 In various localities on the Clyde, the sand of the shore 

 is deep black in colour, and its formation is intimately 

 associated with the multiplication of bacteria which produce 

 hydrogen sulphide (see Ellis (8)). The blackness disappears 



*The adjacent Sea of Marmora and the other neighbouring seas are 

 normal in respect to their content of hydrogen sulphide. 



