NEW YORK, FEBRUARY 2, 1894. 
DUST FROM THE KRAKATOA ERUPTION 
OF 13833. 
| Tue following article is a condensation of some earlier 
publications by Joseph Wharton, of Philadelphia,and formed 
a contribution by him to the papers read at the one hundred 
- and fiftieth anniversary of the American Philosophical 
Society. The work of proving the origin and cause of the 
beautiful glowing skies that are so wellremembered seems 
to have been assumed by this first American metallurgist 
as a recreation for his leisure hours. If Mr. Wharton 
would write of his long, laborious and successful efforts in 
introducing into America the manufacture of zinc and 
nickel and of his metallurgic work at his great Bethlehem 
steel furnaces, he- would add a series of most valuable 
-chapters to the history of the great industries upon which 
the prosperity of our country is based.—Ep. | 
The splendid roseate glows which in the winter of 1883-4 
were visible in the western sky after sunset and in the 
eastern sky before sunrise gave rise to many conjectures, 
but apparently to almost no experiments. A few persons 
believed those glows to be sunlight reflected from the 
under surface of astratum of fine solid particles suspended 
at a great height inthe atmosphere; some thought with 
me that those particles might be volcanic dust which had 
floated to us from the eruption at Krakatoa, but, as no 
one offered any proof of this, 1 attempted on the morning 
of Jan. 20, 1884, to demonstrate it. _ Six miles north- 
ward from the centre of Philadelphia, where I reside, a 
light and fine snow was then gently falling in an almost 
calm atmosphere, presumably from a highaltitude. Of 
that snow, while it was yet falling, I collected about a 
gallon by skimming it carefully with my hands from a con- 
siderable surface in a field a hundred yards to windward of 
my house anda quarter-mile from the nearest windward 
building. 
This very clean new-fallen snow I melted under cover 
in the porcelain bowl it was gathered in, and was at first 
unable to detect any sediment; after maintaining for 
several minutes a gentle rotary movement of the bowl 
in order to bring into its deepest part any solid matter 
which might be present, I poured off the water and evapor- 
ated the remainder. A minute quantity of fine dust was then 
discerned by the tiny vitreous reflections which it gave in 
the sunlight; my practice in chemical analysis, and there- 
fore in weighing small quantities, affords some justification 
for the estimate that the total weight of this dust was less 
than one-hundredth of a grain. 
Under the microscope, where it was immediately placed, 
this dust showed the characteristics of volcanic glass; it 
consisted in part of irregular, flattish, blobby fragments, 
mostly transparent and showing no trace of crystalline 
structure, in part of transparent filaments more or less 
contorted,sometimes attached together in wisps and mostly 
sprinkled with minute glass particles. The filaments of 
glass had about the same diameter as single filaments of 
silk placed on the microscope slide for comparison with 
them. 
Having microscopically examined the dust again and 
again, l ignited it upon platinum to destroy any organic 
matter which might be present, and thereafter found the 
filaments, the flat plates, and the amorphous accretions of 
glass quite unchanged. 
No pyroxene, augite, or magnetite, such as have else- 
where been observed in volcanic dust, was present; it may . 
be assumed that, if at first mingled with the glass, those 
heavier minerals had been dropped during the long voyage 
of more than ten thousand miles of space and more than 
four months of time. 
The capacity of fine volcanic glass to float inthe air to 
considerable distances being a well-established phe- 
nomenon, my examination claims no greater novelty or 
interest than what may be due to the actual finding of such 
glass at so great distance from the point of its ejection. 
In this case two separate ejections seem to be indicated, 
for on several evenings I observed a second and fainter 
glow after the original and stronger glow had entirely dis- 
appeared. A higher stratum of finer particles doubtless 
reflected the sunlight from the greater altitude after the 
sun had set at the lower elevation of the principal dust 
stratum. 
Early in February, 1884, the ship J. E. Ridgeway arrived 
at Philadelphia from Manila by the Strait of Sunda. On 
Feb. 12 I visited that ship, and read on her log-book that 
atro p.m., Oct. 27, 1883, in south latitude 7° 57 and east 
longitude roo® 54’ (about five hundred miles W.S.W. 
from Krakatoa), she encountered a vast field of floating 
pumice, through which she sailed until 7a.m., Oct. 29. So 
abundant was this pumice that the ship’s speed was re- 
duced from nine knots when she entered it to two knots 
at 6 p.m., Oct. 28 ; several hours after that time her speed 
radually increased, as the pumice became less dense, 
from two knots to eight, and finally, when she cleared it, 
to her normal nine knots. No volcanic ash had fallen 
upon the ship, as she arrived too late upon the scene. 
Some of this pumice I took directly from the hands of 
the mate and steward, who had collected it from the sea 
and had kept it in their private lockers. It can scarcely 
be doubted that this pumice was ejected from Krakatoa. 
Now, on placing under the microscope small crumbs of 
that pumice and filaments picked out from its cavities, I 
recognized just such transparent flattish scraps and ragged 
accretions as were among the dust found in the snow-fall 
of Jan. 20, while the filaments, though less varied and in- 
teresting than those then collected, where quite similar in 
character, even to the tiny glass particles sprinkled on 
them. A minor point of resemblence was that the yellow 
color of one little vesicular mass in the dust caught Jan. 
20 was fairly matched by a slight streak of similar color 
in the pumice. 
In March, 1884, I collected dust from the steel works 
at South Bethlehem, Pa., and dust from a’ blast 
furnace there, in order to compare them with the dust 
also 
