30 REPORT—1846. 
destroyed until immediately before death. On opening the thorax, the heart 
was found contracting rythmically. There was a considerable quantity of 
frothy secretion in the bronchial tubes, and this renders it difficult to deter- 
mine if the asphyxia, by which the action of the heart was finally arrested, 
was nervous or pulmonary ; that is, whether the nervous system was affected 
by the want of aération of the blood, or whether the respiratory movements 
ceased in consequence of the action of the acid directly on the nervous 
system. ‘The latter opinion I think the more probable. 
Sulphuric acid, when introduced into the veins, gives rise to exactly the 
same phenomena, the only organ on which it appears to exert any marked 
effect being the lungs, although slight nervous symptoms are produced when 
a considerable quantity has been introduced into the blood. The action of 
these substances when injected into the arteries, and thus applied directly to 
the brain and over the system, without previously passing through the lungs, 
is evidently on the nervous system. Two drachms of the diluted acid, mixed 
with four drachms of water, were injected into the left axillary artery, so as 
to pass into the aorta; in ten seconds all movements ceased ; there was a slight 
spasm, which relaxed ina few seconds. During the continuance of the spasm, 
the pressure in the arterial system was slightly increased, but it rapidly de- 
clined, so that I think the passage of the blood through the systemic capil- 
laries is facilitated, rather than impeded by these substances, All effective 
contractions of the heart ceased a minute after death, probably owing to the 
shock produced by the sudden annihilation of the functions of the nervous 
system, for it retained its irritability some minutes after death, 
With these experiments I conclude the first part of the series of researches 
which I propose to undertake for the elucidation of this branch of physiology. 
I have been engaged on it for the last six years, but I trust the results ob- 
tained fully repay the labour that has been bestowed on it. The action on 
the animal ceconomy of the compounds of twenty-nine of the most important 
elements has been experimentally investigated, and the facts which have been 
observed have led to the discovery of a new law in vital chemistry which 
had escaped the attention of former observers, viz. that the reactions which 
take place between the elements of the living body and inorganic compounds 
are not governed by the ordinary chemical properties of these substances, but 
depend on certain properties they possess connected with their isomorphous 
relations. The verification of this law enables us to undertake the investi- 
gation of the higher chemical phenomena of living bodies from an entirely 
new point of view, whilst its existence accounts for the failure that has con- 
stantly attended attempts to explain the chemistry of animal life by analogy 
from ordinary chemical phenomena. The fact that we now possess the 
means of producing well-marked and definite modifications of some of the 
most important physiological properties of various organs, and this too by 
means of reagents, the laws governing whose action we are acquainted with, 
places in our hands an instrument for discovery which has hitherto been 
wanting in physiological investigations. ‘The enumeration of some of the 
effects that can be produced at pleasure on the more important functions, 
will, I trust, suffice to lead others into this rich field of inquiry. As regards 
the functions of the heart, we can annihilate or increase its irritability, 
quicken or diminish its pulsations, render them regular or irregular, augment 
their force or render thém weaker, destroy the contractility of the auricles, 
whilst that of the ventricles remains ; keep up the circulation of the blood 
many minutes after every sign of life has disappeared, and this too more 
actively than when respiration was being carried on; we can facilitate or 
arrest the passage of the blood through the pulmonary and systemic capil- 
