10 
POPULAR SCIENCE REVIEW. 
an arrest of their functions. The same is the case with the 
knife and scythe-grinders of Sheffield, who get the dust of 
iron and stone into their lungs. The workers in wool, cotton, 
linen, horse-liair, or any of the materials that are taken into 
the air in fine particles, are all liable to consumption, from 
the accumulation of these foreign substances in the air- 
passages of the lungs, and the consequent exclusion of oxygen 
from the blood. Even the dust of ordinary rooms, from 
carpets, furniture, clothes, curtains, and other things, becomes 
a source of impurity of air in our houses, and adds to the 
destruction of health which goes on from the presence of 
carbonic acid. 
One of the most common causes of impurity of air from 
these particles is the unconsumed carbon in the atmosphere of 
towns and cities. It is these particles which blacken linen 
and all white furniture, and the wool of sheep’s backs. It 
exists in such quantities in London, that the air may be filtered 
through fine muslin, and pure carbon collected in considerable 
quantities. It is possible to strain the air of a house, and get 
rid of all these particles. I know one gentleman in the City 
who uses a steam-engine on the premises for the purpose of 
forcing the air through metallic sieves before it enters his 
house. The consequence is, that directly you enter his door, 
the air has all the purity of that at the sea-side or the mountain- 
top ; and instead of the oppression which all London air gives, 
you feel invigorated. This shows what may be done, even in 
the heart of the City. The fact is, air is like water : you may 
contaminate it by suspending impurities in it; but when these 
are withdrawn, it remains as pure as ever. 
The question then comes, if impure air is so dangerous, 
how are we to render the air we breathe pure ? How can we 
get fresh air ? In the first place, every one should be im- 
pressed with the fact, that the open air must always be more 
pure than the air of houses, or any confined space whatever. 
The atmosphere in Cheapside is infinitely purer than any in- 
habited drawing-room at the west end of London. As far as 
fresh air is concerned, a party of ladies and gentlemen would 
be more healthfully occupied in looking at the omnibuses from 
the curbstones in Fleet Street than in the most elegant dining- 
room in Belgravia. 
The night air of Houndsditch is freer from carbonic acid 
than the sleeping-rooms of Mayfair. Hence the importance 
of getting as much into the open air as possible. Children, 
provided they are warm, cannot be too much in the open 
air. It is a most merciful act to take little children from their 
close homes into the open parks ; and this has been done in 
London with the greatest possible advantage. A committee 
