83 
In one person, a youth, the pulse rose on every trial. On 
entering into air with 3 per cent of carbonic acid and no 
organic matter, his pulse rose 6 in two minutes and his 
breathing fell 4. The pulse was so feeble that he could not 
count it; some one helped in the process. He found the air 
very unpleasant. Another young man in two minutes in the 
same air, found that his pulse rose 6 and his respirations 4. 
The action of carbonic acid seems, therefore, in all cases to 
enfeeble the pulse ; at first sometimes to cause a rise, but 
finally to lower the number of the beats. 
This effect is instantaneous or nearly so with air having 
3 per cent of carbonic acid, but diminishes with the amount 
of impurity. It is, however, perceptible with an amount of 
carbonic acid as low as O’ 1 per cent, and probably by taking 
long periods the effect would be found even with smaller 
quantities. This amount is often exceeded in private houses 
and public meetings, where it rises to 0'2 or even 0*3. 
The second effect of carbonic acid is in the breathing, 
which it hastens rapidly, although in some cases it causes a 
diminution of the inspirations. The effect approaches either 
a gasping or a panting. 
The author added that he must leave to physiologists to 
speak of the ultimate effect of such a condition of things, and 
would only observe, that in Dr. Peacock’s inquiries into the 
state of health of the Cornish miners, he found that a feeble 
pulse was one of the peculiarities, a proof that the temporary 
results found in these experiments may be rendered per- 
manent. 
On coming into fresh air the pulse and breathing recovered 
in a few minutes, showing the value of ventilation. 
