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III. Narurat History. 
1. On the different Manners in which Bodies act on the Organs of 
Taste, by M. Chevreul.—Persuaded as I am that many phenomena 
appear complicated to us only because they are the results of many 
causes acting simultaneously, I have adopted as a principle, when I 
examine phenomena of this kind, to endeavour to separate the dif- 
ferent causes which may operate so as to refer to each the effects de- 
pendant on it. Viewing from this point the varied sensations which 
we perceive when substances are introduced into the mouth, I have 
arrived at a satisfactory analysis of these sensations in recognising 
those which are perceived ; Ist. By the touch of the tongue; 2d, 
by the taste; 3d, by the smell. It is generally known that we can 
perceive these three orders of modifications by the introduction of 
substances into the mouth; but since no physiologist that I have 
consulted has indicated the means of recognising the special modi- 
fications belonging to the senses of touch, taste, and smell, I have 
determined to publish the following results, which make part of my 
general considerations on immediate organic analysis, and on the 
application of this branch of chemistry to the history of orgunized 
beings. 
It is not possible to separate the action which a substance intro- 
duced into the mouth exerts on the touch from that exerted by it on 
the taste, but it is easy to distinguish the effects produced on each of 
these senses; for that purpose one must first appreciate the effect 
produced by the substance on the organ of touch by applying it to 
some other part of the body than the tongue, and then this effect 
may mentally be abstracted from that produced when the substance 
is put into the mouth, and by this means the effect produced on the 
taste will be obtained, except that as the tongue is more sensible 
than the skin, the sensation of touch on the tongue will be stronger 
than that on the skin elsewhere. For instance, if a little powdered 
chloride of lime be pressed upon the skin the water of transpiration 
will be solidified by the compound, and a sensation of heat expe- 
rienced, | If, on the contrary, crystallized muriate of lime in pow- 
der be used, it will liquefy, and a cold sensation be felt. It is evi- 
dent therefore that chloride of lime put into the mouth will produce 
heat, whilst the muriate of lime will produce cold, and that these 
effects will be more marked than on the surface of the body, since 
the tongue is more sensible and more humid than the skin. The 
substances which fusing or evaporating on the surface of the body 
produce cold, will also produce the same effects in the mouth if 
they fuse or evaporate there. 
But how are the sensations of smell to be separated from those of 
the touch and taste? Very simply; pressing the two nostrils one 
against the other is sufficient to prevent all sensation of smell, because 
