152 
as a simple body, like chlorine, iodine, or cya- 
nogen, with the metal sodium.* 
It will be seen, then, that the tendency of 
modern researches in inorganic chemistry is to 
prove, that the mode of combination which 
characterises the union of its elements, is not 
by any means so simple as it has been usually 
supposed; but that a binary, a ternary, and 
perhaps even a quaternary compound, may 
perform the part of an element, combining 
with other elements which are really simple, to 
form what are regarded as simple aes com- 
pounds. We shall now enquire what reason 
there is for believing that the compounds with 
which organic chemistry supplies us, have a 
Similar constitution. We must be content, 
however, with selecting one or two examples 
from among the vast number which the in- 
dustry of analytic chemists is constantly bring- 
ing to light. The vegetable a/kaloids have been 
generally regarded as proximate principles, not 
to be separated into simple compounds without 
an entire disunion of their elements. They all 
contain one equivalent of nitrogen ; and there 
is good reason to suspect that this element is 
not equally combined with all the rest, but 
exists in union with hydrogen in the form of 
ammonia, to which the alkaline power of these 
substances is due. Again, camphor was long 
considered a proximate principle of ternary 
composition; but it is now found to be an 
oxide of camphene,—a compound radical con- 
sisting of carbon and hydrogen, which will 
unite, like cyanogen, with simple bodies ; form- 
ing camphoric acid with another equivalent of 
oxygen, and entering with chlorine, &c. into 
other compounds. Lastly, urea may be men- 
tioned, in which the four elements that com- 
pose it may be regarded as existing in several 
forms of binary combination. It contains these 
elements in the following proportions :—2 oxy- 
gen, 4 hydrogen, 2 carbon, and 2 nitrogen. 
These may be considered as existing in the 
form of cyanic acid, ammonia, and water; one 
equivalent of each of these forming cyanate of 
ammonia; and, in fact, by the artificial union 
of these compounds, urea has actually been 
produced. It is by no means certain, however, 
that these compounds exist as such in urea ; 
and various ideas of its composition are enter- 
tained by chemists, on which this is not the 
place to comment. Our object is simply to 
show the analogy in the composition of the 
products of vital chemistry with that of the ar- 
tificial compounds whose formation is subject 
to none but physical laws. Why the chemist 
is not more successful in imitating in his labo- 
ratory the operations of the living economy, 
will presently become subject for consideration. 
An argument employed by many physiolo- 
gists for the existence of a distinct set of vital 
affinities, is founded upon the evident truth, 
that the tissues and fluids which maintain a 
certain composition when possessed of vitality, 
speedily resolve themselves into new combina- 
tions when this has become extinct. Hence it 
is inferred that the affinities which hold toge- 
* See Graham’s Chemistry, p. 158 et seq. 
LIFE. 
ther the elements during life, are of a d 
nature from those which operate in fp 
their subsequent separation. Now, 7 
objected to this inference, that no solid or fi 
compounds which have a disposition to : 
taneous decay after death, can continue 
without change during life ; that the 
the processes of interstitial absorption anc 
position seems to bear a pretty cor 
in every case, with the natural tendency 
composition; and that the maintenance oj 
original combination is not so much ow 
anything peculiar in the affinities 
together its elements, as to the constant re 
of particles in a state of incipient decay 
their replacement by others freshly ui 
Thus, we find that all the most permaner 
of the animal frame, such as the ma: 
tons of the polypifera, the calcareous 
of the mollusca, or the bony scales of fi 
to the possible duration of which geok 
scarcely dare to assign a limit, are extr 
in the living animal, undergoing sear 
interstitial change when once form 
to these in order of durability are the 
structures of animals, and the woody 
plants, whose connection with the circu 
system appears rather adapted to meet 
gencies of growth, injury, or disease, thar 
maintain a constant change es by th 
dency to decomposition. hen we ex 
the softer tissues, on the other hand, 
that the rapidity of interstitial chan 
compensates for the increased tenden 
cay; and that the perfect exercise t 
respective functions imperatively demant 
constant maintenance of their normal ¢ 
tion. Moreover, there are many orgar 
ounds which are as permanentas those 
in the laboratory of the chemist; of th 
are gum, sugar, and many other proximatep 
ciples, which simply require for their pr 
tion such external conditions as are 
to prevent the spontaneous decompos' 
many inorganic bodies. The degree in ¥ 
these are subject to ordinary chemical 
tions will be presently mentioned. It app 
then, to be an inference better founded 
than that first mentioned, that the pre 1 
of the normal constitution of organie 
pounds in the living body, is dependent on’ 
continuance of the vital actions of the € 
nomy, rather than due to its mere possessi 
the property of vitality. In fact, that 
reasonably maintained as an infe 
these phenomena, which we have a 
tempted to prove on other grounds; 
vitality of each tissue, that is to say, its f 
sion of vital properties, is dependent on 
perfect condition of its organisation, and tt 
so far from preserving the organism from dec 
it merely remains until decay has comm 
These inferences are, we think, fully borne 
by the two following facts. When life is’ 
extinguished by starvation, the whole body 
hales a putrid odour even before the o 
of death, and rapidly into putrefactit 
afterwards : here it would seem that the proc 
of spontaneous decomposition, which we ha) 
ie 
A 
