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POPULAR SCIENCE REVIEW. 
in the very best sense of the word: — the science is popularized without 
being vulgarized; the lectures may readily be ‘ understanded of the people,’ 
while they still retain the true ring of sound science. In fine, they are 
essays which may be read with relish by every man of culture, whether 
scientific or not. 
It is to be regretted, however, that some of the lectures published in this 
volume have grown rather old, and have thus lost the edge of their interest. 
Thus the opening discourse on Magnus was delivered as far back as ten years 
ago ! Dr. Atkinson, the accomplished translator of the Essays, has wisely intro- 
duced considerable modifications into the last lecture, dealing with ‘ Academic 
Freedom in German Universities a lecture which, in its original form, con- 
tained remarks on the Universities of Oxford and Cambridge that could 
hardly be reproduced at this time in England, and certainly would not 
reflect the present position of education at those centres. Let us hope that 
Prof. Helmholtz’s second series of Popular Scientific Lectures will be as 
well received by English readers as were the first. 
NATURE’S HYGIENE.* 
I T is a general belief that the vicinity of a pine-forest is exceptionally 
healthy, and of late years the Eucalyptus has also been credited with 
sanitary properties of a very marked character. Mr. Kingzett addressed 
himself some time ago to the chemistry of the subject, in order to ex- 
plain, if possible, the hygienic influence of these trees. His researches 
lead him to attribute their influence to the presence of certain essential oils, 
which, by their slow oxidation, exert a purifying action upon any malarious 
exhalations. Under the influence of air and moisture, the volatile oils of the 
Eucalyptus and of the pine are oxidized, yielding peroxide of hydrogen — a 
powerful disinfectant — and camphoric acid, which is antiseptic. The oil of 
turpentine has, apparently, a higher oxidizing power than the oil of euca- 
lyptus, and hence pines are especially efficacious in rendering a locality salu- 
brious. 
Mr. Kingzett’s studies have led him to prepare an artificial substance 
which he terms ‘ Sanitas ; ’ but a review of a scientific work must not be- 
come a medium for advertizing a new disinfectant. Suffice it to say, then, 
that Mr. Kingzett’s researches in Nature’s Hygiene are so clearly put before 
the public in the present work as to be quite intelligible even to those who 
are not versed in chemical lore. 
* Nature's Hygiene : A Series of Essays on Popular Scientific Subjects, 
with special reference to the Chemistry and Hygiene of the Eucalyptus and the 
Pine. By C. T. Kingzett, F.C.S. 8vo. London: Bailliere, Tindall and Cox. 
1880. 
