th the surface of the
same fluid in another vessel. I next removed the water from the receiver
by _breathing into it_. This was done by filling the lungs with air,
which, after being retained a short time in the chest, was exhaled
through a siphon (a bent lead tube) into the receiver. I then introduced
the lighted taper into the receiver of respired air, by which it was
_immediately extinguished_. Several persons present then received a
quantity of respired air into their lungs, whereupon the premonitory
symptoms of apoplexy, as already given, ensued. The experiment was
conducted with great care, and several times repeated in the presence of
respectable members of the medical profession, a professor of chemistry,
and several literary gentlemen, to their entire satisfaction.

Before proceeding further, I will make a practical application of the
principles already established. Within the last ten years I have visited
half of the states of the Union for the purpose of becoming acquainted
with the actual condition of our common schools. I have therefore
noticed especially the condition of school-houses. Although there is a
great variety in their dimensions, yet there are comparatively few
school-houses less than sixteen by eighteen feet on the ground, and
fewer still larger than twenty-four by thirty feet, exclusive of our
principal cities and villages. From a large number of actual
measurements, not only in New York and Michigan, but east of the Hudson
River and west of the great lakes, I conclude that, exclusive of entry
and closets, when they are furnished with these appendages,
school-houses are not usually larger than twenty by twenty-four feet on
the ground, and seven feet in height. They are, indeed, more frequently
smaller than larger. School-houses of these dimensions have a capacity
of 3360 cubic feet, and are usually occupied by at least forty-five
scholars in the winter season. Not unfrequently sixty or seventy, and
occasionally more than a hundred scholars occupy a room of this size.

A simple arithmetical computation will abundantly satisfy any person who
is acquainted with the composition of the atmosphere, the influence of
respiration upon its fitness to sustain animal life, and the quantity of
air that enters the lungs at each inspiration, that a school-room of the
preceding dimensions contains quite too little air to sustain the
healthy respiration of even _forty-five_ scholars three hours--the usual
leng