1895 - 96 .] Mr W. N. Hartley on Changes in Oceanic Deposits. 29 
were to be interpreted, because, as a matter of fact, the actual 
organism which is the cause of this change has been described and 
named by Zelinsky as the Bacterium Hydrosulphureum Ponticum 
(Proc. of the Russian Physical and Chemical Society , vol. xxv. 
part 5, 1893; also P. and C. C. FranJcland’s Micro-Organisms in 
Water , p. 458). 
This bacterium appears to live upon the cellulose of vegetable 
debris, and it abstracts the oxygen from sulphates. 
I must take exception to Messrs Murray and Irvine’s explana- 
tion of the change which they believe takes place in solutions of 
sulphuretted hydrogen. They cite experiments to show (1st) 
that a solution of sulphuretted hydrogen in pure water, when left 
to stand for a month, was found to be oxidised to sulphuric acid ; 
(2nd) that a solution of sulphuretted hydrogen in sea- water was 
oxidised to sulphuric acid. 
To take this latter case first, the oxidation is caused by the 
bacteria in the manner already explained. In the first case, where 
the sulphuretted hydrogen is dissolved in pure water, there is, 
according to my experience, no oxidation of sulphuretted hydrogen. 
In January of the present year I had six wide-mouthed bottles 
charged with a litre of distilled water, which filled each of them 
to about § its capacity. In succession they were charged to 
saturation with carefully purified hydrogen sulphide, evolved from 
ferrous sulphide by the action of sulphuric acid. These bottles 
were kept in a fume chamber in full daylight, where the morning 
sun could reach them. The temperature varied from 12° to 17° C. 
In five or six days it was found that the bottles did not smell of 
sulphuretted hydrogen. In two of them there had been a slight 
deposition of sulphur. It was thought that the oxidation of 
the sulphuretted hydrogen might not necessarily have formed 
sulphurous or sulphuric acid, but one of the thionic acid. Accord- 
ingly, a very careful examination was made of each liquid. The 
introduction of a little cupric chloride solution gave no black pre- 
cipitate. Iodine solution was not decolorised. Barium chloride 
gave no precipitate. Other experiments were made, but they need 
not be referred to, as no evidence was obtained of any oxidation 
products being contained in the liquid. The gas seems to have 
simply diffused out of the vessels. 
