SCIENTIFIC SUMMARY. 
423 
tion of the sunlight. This same result can also he witnessed by the passage 
of clouds between the sun and mirror. The actual direction in the plant i3 
from the apex of the leaf in sunlight and towards it in the shade. This 
change in direction is so rapid when produced by the shadow of fast flitting 
clouds across the sun’s disc that it would seem that the change of tempe- 
rature could hardly be felt by the plant ; it certainly could not be by an 
ordinary thermometer ; but a heated body properly placed will quicken the 
circulation, as cold will retard it. If he mistakes not, we have here a fine 
demonstration of the conversion of light into heat by its passage through the 
vegetable tissues, and of heat into motion by its action upon the laticiferous 
vessels. 
CHEMISTRY. 
How to Test easily the Fatty Oils. — In a paper published in the Journal de 
Fliarmacie for J uly, Dr. Massie gives a method by which we may readily 
test the relative value. In order to test the purity of the oils, the author 
employs nitric acid (sp. gr. of from 1-38 to 1*41) and metallic mercury. 
Five grms. of this acid, and 10 grms. of the oil to be tested, are mixed 
together in a test-glass of 100 c. c. capacity, and the mixture stirred for a 
couple of minutes. The liquid is then left standing ; and, when the fluid 
has separated into two layers, the colour of these layers is noted. This 
coloration may be from greenish-white to deep brown for the superior, or 
lighter layer ; while the coloration of the acid, always less intense, will 
vary from light yellow to deep yellow, or even rose-red. After a while 
1 grm. of metallic mercury is added, the final result of which addition will 
be the solidification of the bulk of the oil in most cases. 
Alkalinity of Carbonate of Lime. — Mr. W. Skey, who we observe con- 
stantly sends communications to the Chemical Hews , and who is analyst to 
the Geological Survey of New Zealand, sends an interesting note relative to 
the alkalinity of carbonate of lime. He gives the results, which seem to 
show that the salt is alkaline rather than neutral. The following are results 
of several experiments. 1. Carbonate of lime, prepared by igniting pure 
oxalate of lime in a close crucible, at a dull red-heat, gives an intense alka- 
line reaction with reddened litmus-paper, after moistening with distilled 
water, or after re-ignition with pure carbonate of ammonia. 2. Carbonate 
of lime, prepared directly from chloride of calcium and bicarbonate of soda, 
by admixture of their aqueous solutions, and washing the ensuing precipitate 
till all the soda was removed, gave the same reaction with test-paper. 3. 
Limestone, shells (calcareous), calc-spar crystals, and arragonite, are all 
strongly alkaline to test-paper (at least, the samples he had tried were) j 
the powder of any of these substances, washed with distilled water for 
many days, does not seem to lose any of this alkalinity. Lastly (and he 
thinks conclusively), precipitated carbonate of lime, prepared by either 
of the above processes, when agitated with weak hydrochloric acid, in 
successive quantities, until gradually reduced to a minute proportion of its 
original bulk, still manifests this reaction to an eminent degree \ indeed, 
