518 
DES. T. ANDEESOX AXD J. S. FLETT OX THE EEUPTIOXS OF THE 
was a faiiy landscape changed to a blighted desert in a shorter space of time. What 
came of all the carljon comijoimds produced by the destructive distillation ? They 
must have been incorporated in the great black cloud. This was in itself one of the 
most startling and marvellous features of that strange eruption. 
What foi'in the joroducts took, what was their relative amount and the changes 
they passed through, we can only guess. There was little or no oxygen in the 
cloud, and the vegetable matters were practically distilled in presence of dry steam. 
Any oxygen which liad not already combined with the hych’ogen or hydrogen 
sulphide would unite with the cai'hon of the wood to form carbon monoxide or carbon 
dioxide, and the vast numher of volatile oiganic comjDOunds produced by the charring 
of wood in tlie absence of oxygen must all have been there in greater or less 
abundance. Many of these substances must have been capable of producing explosions 
when mixed with air or oxygen in suitable proportions, and we may believe that the 
Ijlack cloud at one stage of its histoi-y was entirely deprived of oxygen and tilled 
with carbon gases. It is probable that the temperature fell too rapidly, and the 
process of mixture with the air was too slow to allow of any considerable part of 
these gases being burnt in the cloud. Before the oxygen could reach them they 
were too cold and too much diluted with steam to ig-uite. We mav in this wav 
explain why the asli which fell in Kingstown on the afternoon of May 7th had an 
odour of organic matters. Mi'. Powell described it to us as strouglv resembling 
that of guano. The ash was moist, and the water mixed with it may have absorbed 
some of the more soluble organic products of tlie great black cloud. 
Even when we were in St. Vincent in the month of June, after a few hours of drv 
weather and sunshine, wreaths of blue smoke would be seen curling up into the air 
from the banks of hot sand whei'e pieces of carbonised wood lay partly exposed to 
the atmosphere. The air then smelt strongly of burning wood, and specimens of 
tar have since been sent us, which were brought down bv the streams when the ashes 
^vere washed away by the rains in tlie llabaka Valley. This tar is a product of the 
distillation of the Avood as it lies embedded in the hot ashes. 
No other ei'Uption AAvrs attended liy these circumstances; no second Uack cloud 
iuA'olved in its mass the forest growth A\ hich for 90 vears had clothed the surface of 
the mountain. It had vanished like a fall of siioav, and in its place Avas now a unste 
of ashes. Carlionic acid and carbon gases there may be in the later outbursts, 
l)ut these are from the magma, oi'igiiial and not accidental ingredients. We may, in 
fact, be certain that tliey are there, but Ave may be equally cei'tain that they are not 
the pi'incipal gaseous components, and that neither does their density determine the 
behaviour of the hea\’y cloud, nor does their ])otential energy furnisli the motive 
lorce Avhich impels it. 
The gases emitted by volcanoes have been the subject of much study, though they 
are still less knoAvn than any of the other products. In the interests of science it is 
desirable that some day Ave may be aide to obtain samples of the gaseous emanations 
