MIASMATIC CONDITION OF THE ATMOSPHERE. 359 
supply an equal amount of nourishment, or the cow falls off 
in flesh, and eventually in milk. We should, therefore, 
hear in mind that the food consumed goes not alone to the 
secretion of milk, but also to the growth and maintenance 
of the bony structure, the flesh, the blood, the fat, the skin, 
and the hair, and in exhalations from the body. These parts 
of the body consist of different organic constituents. Some 
are rich in nitrogen, as the fibrin of the blood, albumen, &c., 
others destitute of it, as fat; some abound in inorganic salts., 
phosphate of lime, salts of potash, &c. 
MIASMATIC CONDITION OF THE ATMOSPHERE. 
M. Houzeau has recently sent in a paperto the Academy 
of Sciences in which the capacity of atmospheric air as a 
vehicle of miasmata is discussed. Amongst the various 
points elucidated by the course of experiments instituted by 
M. Houzeau, one of the most prominent is the frequency of 
the variations undergone by the atmosphere in respect to its 
chemical qualities. Thus if pieces of litmus paper of the 
same size be exposed to the air on the same day and at the 
same hour, in a spot sheltered from rain as well as from the 
solar rays, it will be found that in the country these bits of 
paper will have lost their colour entirely at the end of three 
or four days, whereas in a town hard by they will have under¬ 
gone little or no change. But at the same time it was 
observed that, though the discolouring or bleaching power of 
air is stronger in the open country than in a town, the power 
of converting the blue tint of litmus into red is much greater 
in a town than in the country. In general, the evidence of 
an acid condition of the air, as manifested by this change of 
colour, may be obtained forty-eight hours after exposure. 
The paper subjected to experiment is reddened at its edges 
first. It is often noticed also that the action of the at¬ 
mosphere is different on two pieces of test-paper placed only 
a few yards apart on the same horizontal line, but separated 
by some building, such as a dwelling-house for example, 
standing in an open meadow. At Rouen it was noticed that 
blue litmus is discoloured much more completely at the top 
of the cathedral than at a distance of six yards from its 
base.— Lancet . 
