August 19, 1886] 
is exactly what we find in the case of alcohol. 
primary propyl alcohol,— 
Hee 1St Jel 
sles 
H—C—C—C—O—H 
el 
iat det 1st 
where the hydroxyl is attached to the terminal link, appears to 
produce steadily increasing paralysis of the nerve-centres ; but 
secondary propyl alcohol, where the hydroxyl is attached to an 
intermediate Jink, thus— 
For example, 
Be Et 
hk 
H—C—C—C—H 
| | | 
O 
| 
It 
scratches up or stimulates the nerve-centres before it paralyses 
them (Efron Pfliiger’s Archiv, Band xxxvi., 1467). 
The whole of the carbon compounds, formed on the principle 
of an open chain, appear to have an action more or less like 
that of alcohol, though these are modified by the nature of the 
substances which ‘‘tip,” as it were, the free affinities of the 
carbon links. Thus, marsh-gas, alcohol, ether, chloroform, 
bromoform, and iodoform— 
II 
H H H ini el 
| | | 
H—C—H H—C—C—O—H H—C CX 
| | GENS 
iH iets! inh dat \ 
Marsh-gas Alcohol sO 
HH pe 
aly. 
H—C—C 
la 
Jamiel 
Ether 
Cl Br I 
| | | 
H—C—Cl Br—C—PBr H—C—I 
| | | 
Ol Lr IT 
Chloroform Bromoform Todoform 
all tend to paralyse nerve-centres, and to exert an anesthetic 
action; but the chloral in the chloroform tends to make the 
substance paralyse the heart more quickly than marsh-gas, 
alcohol, or ether, which contain hydrogen alone, or hydrogen 
and oxygen; and in iodoform the effect of the carbonis to a 
great extent swamped by the iodine. 
It is to Liebreich’s recognition of the fact that similar carbon 
compounds possess a similar anzesthetic action that we owe the 
discovery of chloral. The knowledge of the depressing action 
on the heart of chlorine in such compounds led Schmiede- 
berg and Cervello to search for a hypnotic substance which 
should not contain chlorine, with the result that paraldehyde has 
been added to our therapeutic armamentarium ; and the 
stimulant action of ammonia led Schmiedeberg to introduce a 
new hypnotic, urethane, which, like chloral, will produce sleep, 
but, instead of weakening, will stimulate the heart, and is thus 
admissible in cases where chloral might be dangerous. 
Let us now turn to the other class of carbon compounds in 
which the atoms are arranged so as to form a close chain, or, as 
we may call it, a stiff nucleus or shank, to which either single 
hooks or open chains may be attached. ‘This group of carbon 
compounds is termed the aromatic series. The substances be- 
longing to it differ from those of the open chain or fatty groups, 
inasmuch as they tend to stimulate the nerve-centres, and 
produce conyulsions or spasms before paralysing them. But 
the most marked property which they possess appears to be 
their power of reducing temperature, and of destroying low 
forms of life, so that they act both as antipyretics and as anti- 
septics. We have seen that in the open chains of the fatty 
series of carbon compounds, the increased number of links 
appears to increase the activity of the compound, and a condi- 
tion which is similar, in some respects at least, is to be found in 
the aromatic series. For example, in phenol or carbolic acid, 
as it is usually termed, we have one hydroxyl terminal, just as 
in ordinary alcohol ; the other carbon affinities being saturated 
with hydrogen— 
NATURE 377 
When these hydrogen atoms are replaced by methyl, the 
antiseptic power of the phenol is increased, and the increase 
appears to be in proportion to the number of methyl groups 
which are introduced into the compound. Turning again to our 
old illustration of the flesh-hooks, we might compare the benzene 
nucleus to the shank with six points, each of which might be 
armed either with a sharp hydroxyl hook, or with a blunt hydro- 
gen one, or with a carbon chain. The more the blunt hydrogen 
hooks were replaced by chains, the more thoroughly would they 
sweep the pot ; and, in fact, we may say that the more chains 
there are instead of hydrogen, the more thorough is the anti- 
septic action of the compound. 
In the case of antiseptics, all that we want is to insure a 
thorough destruction of the microbes, which give rise to putrefac- 
tion or disease ; but when we come to deal with antipyretics we 
have a more complicated problem before us, for we wish to re- 
duce the temperature in man or the higher animals, while at the 
same time we have to avoid producing any marked action on the 
nervous system in the way either of spasms or paralysis, and 
also to avoid depressing the circulation and causing collapse. 
Now several bodies nearly allied to carbolic acid, and differing 
from it only in the fact that the benzene nucleus in them has 
two hydroxyl groups attached to it instead of one, as in carbolic 
acid, have a strong antiseptic power. These bodies are hydro- 
quinone, resorcin, and pyrocatechin ; they all have an antiseptic 
action, but the strength of their action is very different, resorcin 
having only one-third of the strength, and pyrocatechin only 
one-fourth of that of hydroquinone. This difference in strength 
shows us here, also, how important the position of the hydroxyl 
groups is; because, in pyrocatechin they are close together, in 
hydroquinone they are as far apart as they can be, and in resorcin 
they keep an intermediate position— 
H 
I 
(6; 
| H 
(cs | 
Yo S 
Sl 
H—C (e 
H—C C—H 
cage 
YH 
C 
| 
H 
IL Pyrocatechin Il 
| | 
O C 
| 
ec (e 
He VOSS 
I N 
H—C C—H H—C C—H 
ii—C (—C—-TI H—C C—H 
Sf Snes 
SF SH. 
ce Cc 
| | 
TH ) 
Resorcin | 
i 
Hydroqu‘none 
