32 
Proceedings of Royal Society of Edinburgh. 
mud from 49 fathoms. Two portions of the damp unaltered mud were 
weighed out; one portion, 6 ‘724 grms., was dried at 100° C., and the 
other, 7*881 grms., was treated with deep red Fe 2 Cl 6 in a 100 c.c. 
flask, which was then filled up to the mark with water. 50 c.c. of this 
solution, containing 3*94 grms. damp mud, were acidified with sul- 
'KMn0 4 r , \ 
— grms. per litre), 
phuric acid and titrated with permanganate ^ 
50 
using T9 c.c. To the remaining 50 c.c. with sediment (the volume 
of which may here be neglected) were added 4 c.c. of strong 
hydrochloric acid (12 -5 HC1 grms. per litre), filled up to the mark, 
and allowed to settle. 50 c.c. of this solution, containing 1 ’97 grms. 
damp mud, were further acidified with sulphuric acid and titrated 
with the same permanganate, of which 1 *7 c.c. were used. A litre of 
the above permanganate oxidises 5*6 grms. iron from the ferrous to 
the ferric state. In the first operation, 50 c.c. solution used T9 c.c. 
permanganate, therefore the^whole amount of mud, 7*881 grms., when 
treated with ferric chloride, would require 3*8 c.c. = 0*0213 grm. 
iron. 
After treatment with hydrochloric acid a quantity of solution 
equivalent to 1*97 grms. wet mud required T7 c.c. permanganate, so 
that 7*881 grms. mud would require 6*8 c.c. when treated with both 
HC1 and Fe 2 Cl 6 , which represents 0*0381 grm. iron. Therefore, 
total iron found by 
Permanganate in HC1 + Fe 2 Cl 6 solution, . . 0*0381 grm. 
Deduct Iron found in Fe 2 Cl 6 solution, . . 0*0213 „ 
0*0168 
Leaves Iron present as Ferrous Salt extracted by 
Hydrochloric Acid, ..... 
Of the 0*213 grm. iron found in the first solution we have seen 
that only one-third is to he reckoned as .belonging to the mud, and 
to he taken as forming FeS, so that in 7*881 grms. wet mud 
we have 0*0071 grm. iron present as sulphide, equal to 0*0112 
grm. FeS, and 0*0168 grm. iron present as ferrous oxide extracted 
by hydrochloric acid, equal to 0*0216 grm. FeO. 
The 6*724 grms. wet mud weighed when dried at 100° C., during 
which it was oxidised as well as dried, 2*011 grms., equal to a loss 
of 70*1 per cent. Therefore the dry mud is 29*9 per cent, of the 
damp mud taken. The 7*881 grms. damp mud therefore represent 
