206 



45 milesi; north, Melville, 35 miles; north-east, nearest land 

 25 miles;; east, nearest land .14 miles. Further, 115 points 

 of rain having fallen, the gi^ound was well saturated, and 

 there is no traffic, nor are there any roads her© to create local 

 dust; hence this must bei purely atmospheric, wherever it comes 

 from. In looking at the dust with a small magnifier some 

 small white specks can be seen. These probably are pieces 

 of paint (white zinc) washed off the astragals of the windows 

 in the downward flow of water." 



Sir Charles Todd kindly forwarded the sample of dust, re- 

 ferred to, to us for examination. An examination with a 

 magnifying glass at once showed that the sample consisted lar- 

 gely of organic fibres of some kind, with the specks of white 

 paint referred to by Mr. Christie. The whole weighed only 

 0.2948 gramme. The residue after ignition weighed 0.201 

 gramme, and of this 0.009 consisted of oxide of lead. The 

 small quantity of the sample, combined with the presence of 

 so much impurity, rendered any attempt at a complete chemi- 

 cal analysis useless. An estimation of silica, however, gave 

 63.06 per cent., after estimating and allowing for the oxide of 

 lead present in the ignited residue. This is somewhere about 

 what might be expected from a volcanic dust. An account of 

 3, thorough microscopic examination, which confirms the 

 theory of the volcanic origin of this dust, will be found in a 

 separate note by Mr. Woolnough. 



