1882.] 
A nalyses of Books . 
495 
is a probability that our sense of smell is excited by vibrations of 
a lower period than those which give rise to the sensations of 
light and heat. These vibrations are conveyed by gaseous 
molecules to the surface net work of nerves in the nasal cavity. 
The difference of smells is caused by the rate and by the nature 
of such vibrations, just as differences in tone of musical sounds 
depend on the rate and on the nature of the vibration ; the nature 
being influenced by the number and pitch of the harmonics.” 
To produce the sensation of smell a substance must have at 
least fifteen times the molecular weight of hydrogen. 
The author considers that we must look to radiant heat for 
indications of harmonics of the fundamental vibrations which 
are according to his theory the cause of smell. Prof. Tyndall 
has shown that odours have the power of absorbing heat rays. 
The author considers that smell is more analogous to sound than 
to light, since in a mixture of smells it is possible to recognise 
each ingredient. 
This paper is in our opinion deserving of most careful study, 
and may, or rather should, lead to prolonged experimental 
research. The chief difficulty in the way is that this sense 
affords far more anomalies and idiosyncracies than the senses of 
sight and hearing. Numbers of persons declare that they can 
smell nothing where to others a very distincft odour is per- 
ceptible. 
The same author read at one of the meetings a memoir on 
“ The Connection between Chemical Constitution and Physio- 
logical Action.” Unfortunately it has not found a place in the 
proceedings, and we can merely summarise the author’s conclu- 
sions from the u Reports of Meetings.” He finds that hydro- 
carbons have little, if any, action on the animal organism. 
2. The introduction of oxygen, when the resulting sub- 
stance does not prodhce local irritation, acts on the organism. 
A low molecular weight coincides with a transitory effect ; and 
as it increases the effects become more marked. 3. Compounds 
containing chlorine all affect the organism. Its specific action 
consists in causing irregularity of the heart’s pulsations and in 
lowering the blood pressure. The peculiar action of the carbon 
and hydrogen in compounds containing chlorine is to produce 
irritation in the nerve-centres and in bodies of high molecular 
weight to cause spasms. 4. Nitrogen shows great versatility in 
the part it plays. Many bodies containing it, such as the natural 
alkaloids, have their poisonous action greatly lessened by the 
addition of methyl and similar radicals, while others become 
much more active by their addition. 5. Increase of molecular 
weight corresponds with increased toxical action. 6. Polymeric 
bodies have a different, and in some cases a much more energetic, 
action than the compounds from which they are built up.” 
It is not stated in what manner the compounds in question 
have been introduced into the animal system — a point of some 
