298 The National Geographic Magazine 



yses b and c might almost be duplicates, 

 and they show the low silica and rela- 

 tively high potash, as well as iron and 

 magnesia, of the known St Vincent 

 ejecta ; likewise the high sulphur con- 

 tent, which is probably to be distributed 

 between sulphates and sulphides, as in 

 Steiger's analyses 6 and 7 and the un- 

 published one of my own. But c pur- 

 ports to have been collected from the 

 deck of the S. S. Roddam, while b is 

 from Barbados. How is it possible that 

 two samples so very different in compo- 

 sition as c and No. 2 of Diller's table 

 should have been ejected from the same 

 volcanic vent at the same time and fallen 

 upon the narrow deck of the same 

 steamer? Even had this happened, it 

 seems beyond the bounds of the possi- 

 ble that two samples taken at random 

 should show such differences. Analysis 

 c bears all the earmarks characteristic 

 of undisputed Soufriere ejecta, while 

 No. 2 is as characteristic of that from 

 Pelee when compared with 1 and 3. Is 

 it an unwarranted suspicion that the 

 labels of the specimens b and c, whose 

 analyses appear in the Chemical News, 

 became disarranged, and that they either 

 represent different analyses of the same 

 Barbados dust, or, at any rate, that the 

 Roddam dust is not really represented 

 by c f It is hoped that this point can 

 be made clear by the editor of the 

 Chemical News and the chemist who 

 made the analyses. 



As to analysis a, the announcement 

 in Science implies that it came from 

 Pelee, but there is no proof whatso- 

 ever that this is so. The internal evi- 

 dence of the analysis itself points most 

 strongly to Soufriere as the source, 

 and I shall so regard it until proof to 

 the contrary is forthcoming. The sul- 

 phur is given in the original publica- 

 tion as such, without any statement as 

 to SO :) ; but, as in the case of 6, and 

 probably 5, it may very well be in both 

 sulphide and sulphate state. 



The reason why 4 shows only sul- 



phide sulphur and no sulphate is prob- 

 ably that, because of its being a lump 

 of pumice, the sulphide was not so ex- 

 posed to oxidation as that in the fine 

 sand and dust, which must have been 

 in full contact with air at a high tem- 

 perature sufficiently long to permit of 

 oxidation of a part of the sulphur. 



If the above inferences are justified, 

 we find, then, that while the ejecta from 

 the two volcanoes are of the same gen- 

 eral type and while the material from 

 the same vent may vary in composition 

 within limits, according as it is collected 

 near to or far from the vent, and in 

 coherent or finely divided form, yet 

 there are characteristic differences by 

 which it appears easy to distinguish the 

 product of one volcano from that of the 

 other. 



Possibly, as I have already admitted, 

 further careful investigation will not 

 bear out the conclusions above sug- 

 gested, but the evidences in their sup- 

 port are so strong at present that geol- 

 ogists and chemists will do well to put 

 them to further and decisive proof. 



The analyses afford room for specu- 

 lation in other directions also. If it is 

 true, as said, that the deaths in St Vin- 

 cent resulted largely from strangulation 

 from the fumes of sulphur dioxide, the 

 source of this gas is not far to seek, for 

 the magma before the eruption con- 

 tained sulphide in quantity which, com- 

 ing in contact, while red hot, with air, 

 would be partially oxidized with for- 

 mation of sulphur dioxide. In Marti- 

 nique the testimony as to sulphur fumes 

 in the dust clouds is overwhelming and 

 the odor of sulphur dioxide was, under 

 favorable conditions, perceptible miles 

 at sea ; but it does not appear to have been 

 formed in such quantity as on St Vin- 

 cent, and this stands in agreement with 

 the great paucity of sulphide in the solid 

 ejecta from Pelee, as shown by my anal- 

 yses, which further accounts for the ab- 

 sence of sulphates in them. It is not, 

 in my opinion, necessary to assume the 



