158 
was then gathered I obtained a portion, which, on my return home, 
I examined. 
The results, as might be expected, proved that the substance was 
not sulphur, nor of a sulphureous nature, but a vegetable matter, 
the pollen of the fir — Pinus sylvestris , a tree of which there are 
extensive forests on the banks of the Spey. Before the blow-pipe, 
it burnt with flame, without the slightest sulphureous odour ; and 
left a little charcoal, which, when consumed, yielded a minute quan- 
tity of ash, possessed of an alkaline reaction. When first inflamed 
it made no such noise as that mentioned in the newspaper ; nor in 
burning did it in the least resemble gunpowder. If thrown on the 
fire before it was quite dry, the noise described in that notice might 
have been owing to the sudden conversion of the moisture into 
steam, producing a slight crepitation. Under the microscope it was 
found to consist of grains, some of a spherical form, others, and 
those of largest size, of the same form, with, as it were, a lateral 
addition, as if a smaller grain were attached, or as if the pollen grain 
had been ruptured at opposite points, and a protrusion of some of 
its contents had taken place.* The diameter of a single grain was 
about T oVofli of an inch. The central part of those supposed to be 
ruptured was commonly transparent, and exhibited a delicate granu- 
lar structure, which was rendered slightly brown by the action of 
iodine. The lateral protuberances were more or less opaque. 
Comparing the substance under consideration with the pollen of 
the Scotch fir, taken fresh from the tree, I find there is a perfect 
resemblance in form and colour and other properties. Further, in 
corroboration, it may be mentioned, that at the time of the occur- 
rence of the shower, this fir was in flower in the Highlands very 
generally ; and it is well known that when ripe, as it was at the 
time specified, it is apt to be shaken off by gusts of wind and rain 
in extraordinary quantities, so as to produce what have been called 
“ sulphur-showers.” By Sir John Bichardson I have been in- 
formed that it is not uncommon to see the surface of the great 
lakes in Canada covered with a thick scum of the same kind in the 
vicinity of pine forests. 
What renders the event, as it took place in the Highlands, re- 
* In the pollen of the Scotch fir we find, that by the increase of the in- 
tine the extine is separated into two hemispherical portions, marked by the 
dark spaces at each end of the grains. — Edit. R. S. Proc. 
