TRANSACTIONS OF THE SECTIONS. 
effects upon tlie animal oeconomy 5 which are somewhat analogous 
to those known to be produced by certain varieties of this poison. 
Thus, during the present spring and summer, the saliva, and 
the exhalations from the skin, in almost every individual on 
whom the experiment was made, have been found to be unusually 
acid : the state of the urine also, and other secretions, has been 
most remarkable ; and that in so great a number of individuals, 
as to prove the existence of some widely-acting cause, such as 
has not occurred in our time, or at least since the author of the 
present communication has turned his attention to the subject. 
Should the above conjectures prove to be well founded, they 
lead us to hope that the cause of the present formidable 
epidemic will not be permanent, but will pass gradually away; 
though, from the deep seated and malignant influence which it 
has exerted in organic action, it is probable that several years 
will elapse before its effects will be entirely obliterated. 
The weight of the air is observed to be very unsteady, and 
usually heavier about the new and the full moon. Whether 
this arises from aerial tides has not been satisfactorily deter¬ 
mined. It may, however, he proper to observe, that many of 
the minute differences in the weights of the air at different 
times are more apparent than real, and depend upon the slug¬ 
gishness of the mercurial barometer, which prevents it from 
being an exact measure of the movements of the lighter and 
more mobile fluids. 
Another table was exhibited, intended to show the effects of 
the direction of the wind upon the weight of the air. As these 
observations were made near the western extremity of the me¬ 
tropolis, they were considered as well adapted for illustrating 
the important question, whether the quantity of oxygen natu¬ 
rally existing in the atmosphere be sensibly diminished by the 
innumerable sources of consumption of this most important 
principle constantly going on around us. As before observed, 
the carbonic acid gas was separated in all instances; and as 
this of course would be formed at the expense of an equal vo¬ 
lume of oxygen, the air would be necessarily found lighter, if 
the proportion of this was sensibly diminished. This diminu¬ 
tion in weight, of course, if it happened at all, would happen in 
air from the east, which had travelled over the whole extent of 
the town ; while air from the opposite point might be considered 
as coming directly from the country. With this view the ex¬ 
periments were arranged in such a way that all the results, ob¬ 
tained when the wind came from between the S.W. and N.W., 
and the S.E. and N.E. ; and between the S.E. and S.W., and 
