138 Proceedings of Koyal Society of Edinburgh. 
with, carbonic acid gas. 20 c.c. of strong hydrochloric acid were 
also added, and the flask fitted with a cork pierced by a tube with 
an india-rubber valve. It was then heated on the water-batli for 
half-an-hour, filled up with boiling distilled water, corked, and 
allowed to cool. 50 c.c. were taken for analysis, and titrated first 
with potassium permanganate of grammes per litre ; and 
ou 
then with stannous chloride. 
The stannous chloride used in the case of samples 31 to 46 was 
of such a strength that 1 c.c. = 0*0047 grins. Fe 2 0 3 , and in the case 
of samples 64 to 89, 1 c.c. = 0*0042 grms. Fe 2 0 3 . From the figures 
in Table VI. it will be seen that the bulk of the iron extracted in 
this way is in the ferrous state ; while from column m the total 
amount of iron, expressed as Fe 2 0 3 , extracted in this way is only 
from 40 to 50 per cent, of the amount extracted by prolonged 
digestion. 
Table VII. — Summary , Percentage Composition of Muds. 
No. 
Si0 2 . 
Balance In- 
soluble in 
HC1 unde- 
termined. 
Total 
Insoluble 
.Residue. 
Fe 2 0 3 . 
a 2 o 3 . 
CaC0 3 . 
Loss on 
Ignition. 
Balance 
Soluble in 
HC1 unde- 
termined. 
Total 
Soluble 
in HC1. 
31 
43*64 
16*08 
59*72 
1 5*58 
1*37 
18*3 
3*36 
11*67 
40*28 
32 
43*71 
15*60 
59*31 
5*37 
2*45 
18*4 
3*38 
11*09 
40*69 
35 
27*43 
7*88 
35*31 
3*86 
12*30 
19-1 
3*38 
26*05 
64*69 
36 
42-31 
23*82 
66*13 
6*17 
3*46 
20*0 
3*66 
0*58 
33*87 
39 
44*37 
11*45 
55*18 
6*54 
3’87 
24*5 
3*42 
6*49 
44*82 
41 
33*89 
21*92 
55*81 
6*64 
1*30 
21*0 
3*75 
11*50 
44*19 
43 
32*41 
23*96 
56*37 
6*22 
9*60 
23*6 
3*62 
0*59 
43*63 
45 
32-77 
9*91 
42*68 
4*23 
10*27 
32*4 
2*90 
7*52 
57*32 
46 
31*32 
7*84 
39*16 
4*86 
10*93 
38*2 
3*83 
3*02 
60*84 
64 
22*21 
5*92 
28*13 
4*24 
2*54 
47*1 
10*89 
7*10 
71*87 
65 
14*79 
14*27 
29*06 
3*45 
2*04 
36*6 
6*03 
22*82 
70*94 
86 
34*12 
14*51 
48*63 
6*26 
4*26 
32*5 
5*67 
2*68 
51*37 
87 
36*79 
5*44 
43*23 
5*39 
8*34 
30*8 
6*96 
5*28 
56*77 
88 
37*60 
11*65 
49*25 
4*37 
3*89 
32*5 
4*22 
5*77 
50*75 
89 
37*68 
10*36 
48*04 
4*42 
4*58 
31*8 
5*77 
5*39 
51*96 
In Table VII. the results of the foregoing Tables are collected so 
as to facilitate comparison of the general composition of the different 
muds. 
