( 644 ) 
[October, 
ANALYSES OF BOOKS. 
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. London : Bailliere, Tindall, and Co. 
We have here an interesting treatise on a subject which is by no 
means exhausted. The author contends that these are the great 
natural agents for the destruction of those mysterious entities — be 
they organised or not — which are the cause of epidemics. The 
first fact to be taken into account is the remarkable immunity 
from fevers and other pestilential maladies enjoyed by the great 
island-continent of Australia. Such diseases, if introduced into 
Melbourne or Sydney, die out without spreading. This circum- 
stance is the more remarkable if we reflect that no especial care 
has been bestowed upon sanitary arrangements in the colonies, 
and that, judging from the latitude and the temperature, Aus- 
tralia might seem a fair field for cholera, yellow fever, or plague. 
Its soil and atmosphere are certainly dry, but these features are 
no less to be recognised in Persia, Asiatic Turkey, certain regions 
of India, North Africa, Mexico, and La Plata, where pestilence 
is far from uncommon. 
Of late years it has become prevalent to ascribe the remark- 
able sanitary advantages of Australia to its woods of different 
species of Eucalyptus — a vegetable genus not naturally occur- 
ring in any other part of the world. Nor can we pronounce 
this opinion baseless. It seems perfectly well established that 
certain spots in Italy, Algeria, &c, previously notorious for their 
unhealthiness, have been rendered perfectly safe by the intro- 
duction of this tree. The generally received explanation of the 
sanitary activity of the various species of Eucalyptus is that 
they exhale large quantities of a volatile oil. It has further been 
discovered by the author that this oil, and indeed all the oils 
upon which the aroma of herbs and flowers depends, generate 
peroxide of hydrogen by their action upon air and watery vapour. 
Now as peroxide of hydrogen acts very energetically upon de- 
composing animal and vegetable matter, we can see why a 
Eucalyptus forest should have a beneficial effect upon the health 
of the surrounding district. 
There are still, however, a few questions to be answered before 
we can lay claim to a full knowledge of malaria and of disin- 
fection. We learn that in Queensland, in regions where the 
odour of the Eucalyptus is very distinct, ague is not unknown, 
