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POPULAR SCIENCE REVIEW. 
logical organisations on the globe. The present, being the second report, 
contains in forty-five pages a careful summary of all the important contri- 
butions to this branch of the science which appeared in the years 1872-3. 
We have not space even to bint at the principal works which are 
mentioned. One, however, of special interest to Londoners, is by Dove, on 
the results of a comparison of the temperatures obtained during twenty- 
nine years at Chiswick and at Greenwich, which shows that these two 
stations give very concordant results for the abnormal variations of tempe- 
rature ; but that as regards the mean temperature, taken on the average of 
nearly fifty years, there are noticeable differences, tending to indicate how 
unsafe it is to reason about the change of climate of large cities from the 
comparison of ancient with modern tlieometric records, taken probably under 
very different circumstances. 
Bust from the Heavenly Bodies. — (i Silliman’s American Journal” for 
February 1875 contains a very interesting note of Nordenskiold’s on the 
above subject. He describes that found on the ice in several parts of 
Greenland, and he says of it that this material has much resemblance to 
the remarkable dust found by him scattered on the surface of the ice in the 
interior of Greenland, at a distance of thirty miles from the coast, and to 
which he gave the name cryoconite. This consisted for the most part of 
minute angular crystalline grains, which were colourless and transparent, 
with fragments possibly of feldspar and augite crystals, and some black 
magnetic particles. In an analysis the cryocinite was proved to consist of 
silica, alumina, oxide of iron, manganese, magnesia, potash, soda, with 
traces of chlorine and organic matter, and to give the oxygen ratio for the 
protoxyds, alumina, silica and water, 2 : 3 : 14 : 1. Its specific gravity is 
2*63, and the crystalline form is monoclinic. He shows that the cryoconite 
must have had either a cosmical origin, or have come from Jan Mayen, or 
else some unknown volcanic region in the interior of Greenland, while the 
presence of cobalt, and probably nickel, would seem to prove that a part of 
the dust at least had a cosmical origin. He finally comes to this con- 
clusion — that small quantities of a cosmical dust, containing metallic iron, 
cobalt, nickel, and phosphoric acid, and also a carbonaceous organic matter, 
falls upon the earth along with atmospheric precipitation. 
MICROSCOPY. 
How to Stain Thin Leaves or Green Sections for the Microscope. — Dr. 
C. Johnston adopts the method described below, which be has given in 
,an essay on the subject in the ‘‘Monthly Microscopical Journal:” — 
“ Colour must first be removed, or else staining would be of little service. 
The bleaching is to be accomplished through the agency of Labarraque’s 
solution of chlorinated soda, in which the objects ought to be macerated, 
and suffered to remain until perfectly achromatic and transparent. Im- 
mediately thereafter others must be transferred to distilled water for an 
hour or two, and then to a 3 per cent, solution of oxalic acid in 50 per cent, 
alcohol, which neutralises the soda and disposes the tissue to accept the 
