376 
NATURE 
[August 19, 1886 
very greatly if the priests had to go fishing in the brazen sea of 
Solomon, for there, with a short handle, they might not be able 
to reach the tit-bits in the middle, and if the handle were too 
long, they might go plunging their hooks about the opposite 
side of the vessel, with the same result as if the handle were too 
short. Now, in the drugs which we use in medicine, we may 
find a certain analogy with these flesh-hooks, some part of the 
drugs being comparable to the hooks, and others to the handle. 
Perhaps the analogy would be even more correct if we were to 
regard the hooks as having movable points, which could be 
taken off and replaced by others of a different form or sharpness. 
If we take alkaline salts as an example, we may regard the base 
as the handle, and the halogen as the hook ; and by modifying 
either of these, we may alter the parts of the body affected and 
the manner in which they are affected. We might, indeed, com- 
pare chloride of sodium, in which we have the chlorine attached 
to sodium, with the low molecular weight of 23, to a hook with 
so short a shank that it did not reach the big joints lying in the 
middle of the cauldron ; while potassium, with a molecular 
weight of 40, was just long enough to do this; and rubi- 
dium, with a molecular weight of 85, was so long as to go 
plunging about on the other side. In fact, we find that this 
is very nearly what occurs in the muscles of the animal body 
after the administration of the chlorides of sodium, potassium, or 
rubidium ; for, while potassium chloride is a powerful muscular 
poison, the action of sodium and rubidium chlorides on the 
muscles is very slight. 
We have seen what changes would follow alterations in the 
shank of our flesh-hook ; now let us see the effect of altering 
the prongs. If we put’on a small one like chlorine, it may go 
dragging about catching everything, but bringing out nothing ; a 
bigger one, like bromine, may lay hold of a lung or a brain ; 
and a bigger one still, like iodine, may lay hold of a big joint. 
Now, what we find in the body seems to be somewhat similar. 
The chlorides circulate in the blood without producing any 
marked alteration beyond that which is due to the substance 
with which the chlorine is combined. The bromides attack the 
brain and nerve-centres, and the iodides tend more especially to 
affect the muscles and the glands. 
It is evident that another important factor besides the sharp- 
ness of the hooks is the number of prongs, and the three- 
pronged hook seems to be the generally effective one. Now, in 
pharmacology, there is one substance—nitrogen—which appears 
sometimes to have three, and sometimes five prongs, or affinities, 
as chemists term them, and it is a substance having a very 
general and powerful influence over the body. When combined 
with hydrogen in the form of ammonia or of ammoniacal salts, 
it affects nerve-centres, motor nerves, and muscles, tending first 
to stimulate and then to paralyse them. But, as we would 
expect, the effect of the ammonia is modified by its combination 
with iodine, chlorine, and bromine ; and we find that, while 
the ammonium-chloride generally attacks the spinal cord and 
causes irritation, ammonium-iodide paralyses the motor nerves 
and muscles. 
When nitrogen has oxygen combined with it in place of 
hydrogen, so as to form nitrous acid, its action is exerted more 
especially upon the blood and blood-vessels, so that it causes 
the blood to become chocolate-coloured, and the blood-vessels 
to dilate. This power of dilating the vessels is sometimes ex- 
ceedingly useful in the treatment of disease ; and we have been 
enabled to vary the action of our drugs so as to attain, toa great 
extent, the end we desire, by our knowledge that the action 
depends upon the nitrous acid, and not on the substance to 
which the acid may be attached ; or, to return to our own com- 
parison, the effect depends on the nature of the hook rather 
than on the kind of shank to which it is attached. Thus, where 
rapid dilation is desired, we use nitrite of amyl; but where a 
slower and more prolonged action is desirable, we employ nitrite 
of soda or nitro-glycerine. 
In some useful tools we have the two ends serving different 
purposes: one end, for example, being a hammer and the other 
end a claw for extracting nails ; and we can easily imagine a 
flesh-hook constructed on the same principle, one end, let us say, 
having the prongs widely apart, and the other the prongs close 
together. With such a hook, it is evident that the viands which 
were fished up would be different according as one or other end 
was put into the pot, for the close prongs would bring up 
delicate little pieces which would simply slip through the wide 
ones. If we carry our illustration a step further, and suppose 
this hook to consist of two parts attached to one another by 
certain prongs, while others were left free, we can see that, if 
only one prong were left free in each part, but these prongs were 
of different shapes, the pieces obtained by the man using it would 
be of a different kind, according as the prong belonged to one end 
or the other. Now we seem to find something of this sort in the 
union of nitrogen with carbon. Carbon is a substance with four 
affinities, while nitrogen appears sometimes to have threeand some- 
times to have five. When the nitrogen and the carbon are 
united in such a way that four affinities of each are connected 
together, leaving one free affinity or prong belonging to pentad 
nitrogen, thus, —N=C, the compound is exceedingly poisonous ; 
whereas, when the free affinity or prong belongs to the carbon 
and the other three affinities are joined to triad nitrogen, thus, 
—C=N, the compound is comparatively innocuous. 
This fact shows us how very important the nature of the free 
affinity in the compound is in regard to physiological action. 
We have just pictured to ourselves an instrument of two parts, 
joined together by small hooks, and consisting, in fact, of two 
links. In this instrument the links differ a good deal from each 
other ; but one link—namely, carbon—has-a great power of 
uniting with itself, s> as to form long chains, straight or 
branching, thus— 
Pk el 
=c=czc= 
| | 
Sez 
OS 
It also forms what we may possibly regard as close chains, so 
stiff as to act the part of a shank, to which single hooks or long 
open chains may be attached. We may represent it graphically 
thus— 
he ake 
=6— Cao 
keh | 
Now, if any of Eli’s successors wanted to fish in Solomon’s 
brazen sea with hooks attached to a flexible chain instead of to a 
stiff shank, the results of his fishing would not only depend on 
the hooks he used, but on the length of the chain, on the kind of 
chain, single or branching, and on the position of the links to 
which the hooks were attached. 
Now, in the series of chemical substances to which alcohol 
belongs we have an illustration of the modifications in physio- 
logical action which are produced by the length of the chain, 
the kind of chain, and the position of the hooks. The links, in 
the case of alcohol, consist of carbon atoms attached to each 
other by one affinity, so that each terminal atom, or link, has 
three affinities, or prongs, and the intermediate links have two 
each unattached, thus— 
Leal 
—C—C—C— 
allel 
We may regard one prong of one terminal link as furnished 
with a sharp point, to which we give the name of hydroxyl, 
while all the others are furnished with blunt hydrogen points, 
thus— 
13D) Jab isl 
(aes | ae 
H—C—C—C—O—H 
[egal al 
let et si8t 
All the alcohols attack the nerve-centres, and paralyse the brain, 
the spinal cord, and the centres of organic life in the medulla 
oblongata. In large doses they all produce death, and the 
longer the chain the more deadly do they become, until the 
chain is so heavy that it can hardly be used at all, or, in other 
words, till the alcohol becomes so solid that it will not readily — 
enter the body and produce its toxic action. 
If we fix the sharp hydroxyl on one of the intermediate links, 
instead of the end one, we would naturally expect that it might 
simply scratch the pieces of meat instead of pulling them out, 
as it might do if it were attached to the terminal link ; and this 
