ee Kxamination of the Atmosphere. 93 
place often if these are neglected. In the above-mentioned experi- 
ments on the liver of the sheep, the pressure employed was surely 
too little to rupture the “ biliary tubules,” and the exceedingly slow 
and gradual descent of the liquid would be sufficient reason to deny 
such an accident. The walls of the capillaries are very elastic, a 
fact which I have often observed, by stretching them to one-third 
more of their original length by means of the microscopic dissector. 
To the best of my knowledge, Mr. Natilis Guillot is the only 
author who has asserted the existence of a natural communication 
between the hepatic ducts and lymphatics. 
VI.—A Microscopie Examination of the Atmosphere. By Grorar 
Sicerson, M.D., Cu.M., F.L.S., Member of the Royal Irish 
Academy. 
I pestre to lay before the readers of the ‘Monthly Microscopical 
Journal’ some of the results detailed in a lengthy paper which I 
read at the last meeting of the Royal Irish Academy [June 13], 
and which was entitled “ Further Researches on the Atmosphere.” 
In a paper read at the January meeting I communicated the 
results of an examination of the “Sea Breeze,” of “ Country Air,” 
and of “ City Air,” making reference to house-air likewise. Some 
question was made at the time with regard to the muriate of 
ammonia, which I described as found in combination with mucus in 
the city air. In order to have a faithful representation of its exqui- 
site dendritic crystallization-forms, I had had photo-micrograms 
taken in June, 1869, but I did not find photography so accurate as 
the pencil. The chemical examination made by Dr. Angus Smith, 
by which he has found “albumoid ammonia” in the atmosphere, 
seems to corroborate my view. 
In order to obtain an accurate knowledge of what is usually and 
what is occasionally present, it appeared requisite to make a careful 
examination of particular atmospheres as well as of the general air. 
A commencement was made in the previous paper, when the sea 
breeze, country air, and city air were investigated, as well as the 
more limitedly special air of our dwellings. The examination of 
special atmospheres has since engaged my attention. In the paper 
to which I have referred I detailed my mode of operation, and 1 may 
now proceed to describe the objects found in the sediment from the 
air taken from ledges above man’s height, and observed likewise in 
the atmosphere. 
And first of iron-factory air, a friable black dust—on examination 
this was found to be made up of particles of carbon, of ash, and of 
iron. The carbon formed the largest masses, the ash-particles were 
H 2 
