Harriteyv—On Haze, Dry Fog, and Hail. 049 
felspar and quartz sand, or in other words, it was a red felspathic 
sand, such as is found in the desert of Sahara and in Egypt. 
Black rain falls occasionally at distances apparently remote 
from manufacturing centres. Rain of this character, accompanied 
by intense darkness, descended upon an area of nearly 500 square 
miles in the North of Ireland, in February, 1898, during a spell 
of north-easterly wind. 
In May, 1899, an equal area in central and south-western 
England received a similar fall. 
‘he precise atmospheric conditions necessary for raising of dust 
or smoke into the upper parts of the atmosphere, and the con- 
centration and descent over special areas, is not fully understood. 
On December 27th, 1896, there occurred over Melbourne 
and a considerable area of Victoria, an unusually heavy fall of 
dust of a red colour, which was carried down by accompany- 
ing rain. This was examined microscopically, and found to 
contain diatomaces ; it was therefore of terrestrial origin. Its 
chemical analysis, made by Mr. Thomas Steel, F.c.s., showed that 
it agreed closely with the composition of volcanic soils from such 
widely separated localities as Northern Queensland, New South 
Wales, and Fiji.’ 
In such facts we have abundant evidence of the transference of 
great bodies of dust from the Harth’s surface to far distant 
regions by the operation of gentle air-currents. In February last, 
I communicated to the Royal Society a paper, by Mr. Ramage 
and myself, on the mineral constituents of dust and soot from 
various sources.* 
Dust was separated from hail, rain, and sleet which fell in 
Dublin ; voleanic dust came from different sources, and pumice 
from Krakatoa. We collected soot from different chimneys, flue- 
dust from gas works, from iron furnaces, and from copper- 
smelting works. Flue-dust from vitriol works, and iron pyrites 
from coal, also the dust from coal ashes were analysed. The 
localities from which the specimens came were situated in Ireland, 
England, Wales, the United States, New Zealand, Krakatoa, 
Vesuvius, and South America. We also examined meteorites 
1 Nature, vol. 63, p. 472. 
2 Australasian Association for the Advancement of Science, January 10th, 1898. 
3 Proc. Roy. Soc., vol. 68, p. 97, 1901. 
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