1895-96.] Mr W . N. Hartley on Changes in Oceanic Deposits. 27 
and shows that it acts like an alkaline sulphydrate in converting 
ferric hydroxide into ferrous sulphide. When air acts on the 
ferrous sulphide, sulphur separates according to a well-known 
reaction, and ferric hydroxide is re-formed. 
In the absence of manganese it is doubtful whether a similar 
action takes place through the agency of calcium sulphate being 
reduced to calcium sulphydrate, as will appear from a careful study 
of the following facts which have already been ascertained. 
It was shown by Lothar Meyer, as far back as 1864, that the 
sulphuretted hydrogen in mineral waters is very generally a product 
of the algae which are found in them ( J . fur Praktische Chemie , 
vol. xci.). Cohn described a bacterium found in a well-water which 
evolved sulphuretted hydrogen {Beitrdge zur Biologie cler 
Pflanzen , vol. i. part 3, 1875). Etard and Olivier showed that in 
mineral waters sulphate of lime yields sulphuretted hydrogen, or 
even free sulphur ( Comptes Renclus , 1882). Hoppe-Seyler 
described the fermentation of cellulose ( Zeitschrift fur physio- 
logisclie Chemie , vol. x. part 5, 1886) by the agency of the bacillus 
amylobacter, and showed that the organism resolves the cellulose 
into equal volumes of methane, CH 4 , and carbon dioxide, C0 2 . 
When, however, there were sulphates present in the water the 
volume of carbon dioxide was greatly increased, being ten volumes 
of C0 2 to one volume of CH 4 . This arises from the oxidation of 
the methane by the sulphate in accordance with the following 
equation : — 
CII 4 + CaS0 4 = CaC0 3 + H 2 S + H 2 0. 
Sergius Winogradsky has made a most careful investigation of 
the life-history of various species of sulphur-bacteria or beggiatose 
(Botanische Zeitung , pp. 490-610, 1887). 
These organisms separate sulphur from sulphuretted hydrogen, 
and this gas is quite indispensable to their life ; but they cannot 
live in a saturated solution of H 2 S, as was believed by Cohn. 
The sulphur which the beggiatose separate from H 2 S is oxidised 
by them into sulphuric acid, and in this way the carbonates formed 
by the fermentation of cellulose accompanying the reduction of 
sulphates and in presence of sulphuretted hydrogen are subse- 
quently decomposed according to the two equations : — 
