386 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[November 16, 1872. 
valuable series of experiments which he had undertaken 
for the purpose of determining whether any relationship 
exists between the atomic weight and physiological 
activity of elementary bodies. As a result of this inves- 
tigation, he has found that the metals are more active 
physiologically according as their atomic weights are more 
elevated. For example, in reference to sodium, potassium 
and thallium: sodium, with an atomic weight of 23, is 
almost inert; potassium, with an atomic weight of 39, is 
active in moderate doses ; and thallium, with an atomic 
weight of 204, is a dangerous poison, nearly as poisonous, 
indeed as lead, with an atomic weight of 207. On com¬ 
paring magnesium, zinc and cadmium, it is seen that 
magnesium, with an atomic weight of 24, is starcely 
more active than sodium (23), for the salts of the former 
are prescribed in about the same doses as those of the 
latter; while zinc, with an atomic weight of 65, is a 
dangerous substance, although much less so than cad¬ 
mium, whose atomic weight is 112. In reference to the 
metalloids, Dr. Rabuteau has found that those which are 
diatomic , as oxygen, sulphur, selenium and tellurium, 
conform to the same law as the metals. The monato¬ 
mic metalloids, however, are governed by a law which is 
the reverse of this; a fact which had previously been 
pointed out by Bouchardat and Stuart Cooper, who 
observed that chlorine (3 5’5) is more active than bro¬ 
mine (80), and the latter more so than iodine (127). 
_ The. support that is thus given to the theory of a rela¬ 
tionship between chemical property and physiological 
effect, is greatly strengthened when we find that the 
physiological action of substances may be modified by 
changing their chemical properties. One of the most 
remarkable examples is that afforded by amygdalin. 
This neutral principle is derived from bitter almonds, 
and is a substance devoid of physiological activity. 
There occurs along with it in the bitter almond another 
principle, emulsin, also a substance possessing no physio¬ 
logical activity. A large dose either of amygdalin or of 
emulsin alone may be injected into the circulation of an 
animal without any effect whatever being produced. 
When, however, the two substances are together injected, 
even at points far removed from each other, physiolo¬ 
gical effects are produced with great activity, and death 
occurs. The originally inert amygdalin becomes a 
powerful poison, the result of a modification in its che¬ 
mical properties—a modification which may be easily 
recognized by comparing the odour of the moistened 
amygdalin with that of the mixture of amygdalin, emul¬ 
sin and water, and which may be represented by the 
equation:— 
Hydride of 
Amygdalin. Benzol. Prussic acid. Glucose. 
C 20 H 27 NO u + 2H 2 0 = C 7 H 6 0 + CNH+ 2C 6 H 12 C 6 . 
Another example is found when morphia is acted upon 
by hydrochloric acid at a high temperature by which its 
chemical properties are modified and its composition 
changed so that one equivalent of water is separated 
from it. Morphia thus modified possesses physiological 
action very different from that of morphia itself. In 
place of producing hypnosis, this changed morphia—to 
which the name of apomorphia has been given—acts as 
a powerful emetic, so powerful, indeed, that in man eme¬ 
sis occurs within a very few minutes after the one- 
thirteenth part of a grain, or even a smaller dose, has 
been subcutaneously injected. 
On the general law, that the physiological action of 
a substance may be modified by changing its chemical 
properties, has been founded the application of chemical 
antidotes for poisons. The chemical properties of arse- 
nious acid are changed by hydrated sesquioxide of iron 
• or of magnesia, those of tartar emetic by tannin or al¬ 
bumen, those of lead by sulphate of magnesia, those of 
prussic acid or soluble cyanides by proto and persalts of 
iron, those of oxalic acid by carbonate of lime, and those 
of morphia, strychnia, and various other alkaloids by 
tannin or iodine and as a result of this change 
the physiological properties of these substances are 
modified. 
To the recognition of this law, likewise, therapeutics 
has become indebted for the introduction of a remedy 
which every one must admit has proved of the greatest 
value in the treatment of disease. Although chloral 
was discovered more than thirty years ago, it was not 
until 1869 that Liebreich ascertained and investigated 
its important physiological action. The chemical 
change anticipated was the decomposition of the chloral, 
after its introduction into the circulation, by the alkaline 
salts present in the blood. This decomposition may 
readily be seen by adding some caustic alkali to a 
tolerably strong solution of chloral hydrate ; the result 
being the precipitation of minute globules of chloroform 
and the simultaneous formation of formiate of the base 
that is added : — 
Pormiate of 
Chloral. Chloroform. Potassium. 
C 2 C1 3 H0 + KHO = CC1 3 H + co 2 kh. 
The principle that a connection exists between the 
chemical properties and the physiological action of active 
substances, receives a further support from several well- 
known facts, which show that the physiological action 
of active substances may be accompanied with distinct 
chemical reactions between them and certain of the vital 
structures. Thus, in producing its violent corrosive action 
sulphuric acid withdraws the element of water from the 
tissues, liberates the carbon of the ternary hydrocarbons 
and separates from them their basic constituents. The 
analogous corrosive effects of nitric acid are accompanied 
with the oxidation of tissue-elements, and combinations 
with electro-positive substances, and with the formation of 
xanthoproteic acid—by the last of which reactions the 
characteristic orange staining of the skin and fibrous 
tissues is caused. The local effects of the caustic alkalies 
are also accompanied with well-defined chemical 
changes in the vital structures on which they act. 
One of the most striking examples of a definite change 
of chemical property accompanying the physiological 
action of a substance is that afforded by carbonic oxide. 
Claude Bernard, the distinguished physiologist, dis¬ 
covered that carbonic oxide renders the blood of a 
marvellously florid colour, that it thrusts out oxygen 
from that fluid, and that its action is in some way related 
to the latter effect. More recent investigations, especially 
those of Lothar Meyer and Hoppe Seyler, have confirmed 
Claude Bernard’s results, and also shown that carbonic 
oxide forms a definite chemical union with the haemo¬ 
globin of the blood. The resulting compound is one of 
great stability ; so much so that carbonic oxide-haemo¬ 
globin resists the action of powerful reducing agents. 
The physiological action is the direct result of the change 
in the chemical properties of haemoglobin—a change 
which has, among other effects, that of preventing those 
chemical interchanges between it and the oxygen of the 
air on which life depends. The relation of the great 
stability of the combination between carbonic oxide and 
haemoglobin to certain of its physiological effects is 
also apparent, for the serious symptoms which are pro¬ 
duced by the most minute quantity can be recovered 
from but slowly. They can, however, be recovered from; 
and again we find that a chemical explanation may be 
adduced for this physiological change, as it has been 
recently discovered that, under the prolonged influence 
of oxygen, the carbonic oxide is at last liberated from 
its combination with the haemoglobin. 
There is some reason for supposing that somewhat 
similar chemical effects are produced during the action 
of prussic acid; and it has been shown by the careful 
and elaborate observations of Dr. Gamgee that nitrites 
conduct themselves towards haemoglobin in an analo¬ 
gous manner to carbonic oxide—a fact which may ex¬ 
plain ^certain of the phenomena produced by nitrite of 
amyl. 
These various illustrative examples are sufficient to 
