1890 - 91 .] Mr J. Y. Buchanan on Sulphur in Marine Muds. 35 
filled up with the manganous sulphide at the time of preparation, 
have never been opened since, though they have all the time been 
exposed to the light, and are exactly in the condition in which they 
were when bottled nine and a half years ago. There is no trace of 
oxidation. 
Manganous Sulphide and Hydrous Ferric Oxide . — Both substances 
are used, suspended in distilled water. If the ferric oxide he 
cautiously added to the sulphide of manganese, and both suspended in 
w^ater, the red patches are seen to disappear, and the general colour 
of the suspended matter becomes rather lighter in colour than the 
MnS, and there is no formation of FeS. If further additions of 
Fe 2 0 3 he made, red flakes deposit themselves. They do not appear 
to he unaltered Fe 2 0 3 , hut are exactly like the “red cherty par- 
ticles ” of manganese bottoms. On still further additions of Fe 2 0 3 , 
the colour changes quickly, though not instantaneously, to black, 
with, however, a large admixture of white particles, the two being 
easily seen to he perfectly distinct. There is also a quantity of pre- 
cipitated sulphur which remains floating in the liquid long after 
the heavy matter has subsided. 
Prosecuting this line of experiment, I made three mixtures in 
suitable flasks. 
Ho. 1 contained MnS and Fe 2 0 3 , the MnS being in excess. 
There was formation of red cherty particles, hut nothing black. 
No. 2. The same substances, but containing the Fe 2 0 3 in excess ; 
the mixture quickly turned black. 
No. 3. The same as No. 2, only it was made up with warm water, 
and it turned black almost at once. 
These experiments were repeated, and with the same results. 
The above flasks, Nos. 1, 2, and 3, were corked up and allowed to 
stand over night. No. 1 contained numerous black particles, as 
well as red cherty ones, and an excess of MnS as well as sulphur. 
Nos. 2 and 3 were much as they had been the night before, except 
that the white particles had almost entirely disappeared, as also all 
red particles. The reactions are considerably accelerated by heat. 
On examining the contents of each of these flasks, no peroxide of 
manganese was found, hut large quantities of sulphide of iron. 
The likeness in the red flakes to the cherty particles of the bottom 
muds in the manganese districts of the South Pacific, and of the 
