28 COTTON WOOL AND ALPINE AIR. 



But more than this, Dr. Tyndall professes to be 

 able to bring " the air of the highest Alps into the 

 chamber of the invalid." This grand result he pro- 

 poses to achieve by causing the dusty air to traverse 

 cotton wool, by which operation the dust which had 

 been demonstrated together with the germs supposed 

 to be mixed with it are filtered off. Even Dr. Tyndall 

 will scarcely be inclined to deny, after a little quiet 

 reflection, that the promise to bring Alpine air into 

 the London sick rooms, may appear to unromantic 

 people who actually attend upon invalids more like 

 the result of emotional excitement than a conclusion 

 deduced from any exact methods of observation or 

 experiment. 



By the physical method of examination, particles of 

 wool and cotton and hair, scales and other particles 

 from insects, and starch and soot, and all the other con- 

 stituents of dust, alive and dead, organic and inorganic, 

 are illuminated so as to form one confused ray, which 

 can be seen at a great distance ; but, it need scarcely 

 be said, the brightest light the physicist can cause to 

 beat upon them fails to reveal the nature of the 

 several dust particles, or enable anyone to distinguish 

 the living particles from the lifeless debris ; or the 

 virulent disease germs, should there be any, from the 

 harmless dust. Now, instead of burning all the organic 

 matter together, the living and the lifeless with the 

 non-living, including that which exhibits form and 

 structure, and that which is formless and structureless, 



