THE ERUPTIONS OF MAY, 1902, AT THE SOUFEIERE IN ST. VINCENT. 
327 
crystallisation, magnetite and apatite also are present in all the samples. There are, 
however, points by which these dusts can be distinguished from one another. The 
1812 dust is by far the richest in brown glass,* often very free from microlites ; it 
occurs largely as minute rounded spongy lapilli. The dust of October, 1902, which 
is very fine and pale coloured, is also rich in glass, which occurs as minute broken 
splinters. In this dust also broken felspars are very common, which circumstance 
Analyses of Volcanic Dusts from St. Vincent, which fell in Barbados. 
I. 
II. 
III. 
SiO, 
52-81 
50-722 
51-523 
Ti0 2 
0-95 
1-150 
1-000 
AL0 3 
18-79 
12-550 
21-648 
Fe 2 0 3 
3-28 
9-484 
j 6-372 
FeO 
4-58 
4-676 
MnO 
0-28 
0-450 
— 
(CoNi) O 
0-07 
— 
— 
CaO 
9-58 
10-100 
10-000 
MgO 
K,0 
5-19 
5-911 
4-716 
0-60 
0-531 
0-675 
Na,0 
3-23 
3-451 
3-551 
P 2 0 5 
0-15 
0-192 
0-141 
S0 3 
0-33 
0-108 
0-124 
Cl 
0-14 
— 
— 
HoO - 105° C. 
0-20 
0-130 
0-190 
H,0 +105° C. 
0-17 
0 • 545 
0-060 
100-35 
100-000 
100-000 
I. Dust that fell on Barbados, May 7 and 8, 1902 (anal. Dr. W. Pollard, ‘ Quart. Journ. Geol. Soc.,’ 
LVIII., p. 369, 1902). 
II. Dust that fell on Barbados, March 22, 1903 (anal. Professor D’Albuquerque, ‘West Indian 
Bulletin,’ vol. IV., p. 98, 1903). 
III. Dust that fell on Barbados, May 7 and 8, 1902 (anal. Professor D’Albuquerque, ‘West Indian 
Bulletin,’ vol. III., pr 283, 1902). 
probably accounts for the greyish colour of the samples. Olivine is comparatively 
infrequent. The dust of March, 1903,t is also fine grained, but is very dark in 
colour, being deep brown. This dust contains more olivine than any other of the 
specimens examined, and its crystals are often coated with very dark films of glass. 
Professor Longfield Smith|§ has noted that this dust is richer in ferromagnesian 
* Prior, T. G., ‘ Quart. Journ. Geol. Soc.,’ LVIII., p. 370 (1902). 
t Bonney, T. G., “Notes on March Dust from the Soufrifere,” ‘Nature,’ vol. 67, p. 584 (1903). 
| Smith, Longfield, “ Volcanic Eruptions in the West Indies,” ‘ West Indian Bulletin,’ vol. IIP, p. 271, 
1902). 
§ Anon., “Notes on fall of Volcanic Dust at Barbados, March 22, 1903,” ‘West Indian Bulletin,’ 
vol. IV., p. 91 (1903). 
