23 
us to breathe. He had for many weeks collected dew on a 
grass lawn in a garden, and from it had obtained organic 
matters unquestionably collected from surrounding objects, as 
it was known on one occasion to smell of flowers. If this 
entered into putrefaction it would of course be unwholesome, 
but what kind of disturbance of health it would cause it must 
be for others to find. The evening air of a rainy country 
like this is less dangerous than that of some other climates 
where there is more both evaporated and condensed, and 
neither wind nor rainJo remove it. Notwithstanding this, he 
believed that more than the dew was required, especially in 
northern climes. 
The President also said, that when sitting in a railway 
carriage with his friend, Mr. James Young, of Bathgate, that 
gentleman observed that the particles of dust which floated 
in the air seemed to shine with a metallic lustre. Dr. S. 
immediately collected some, and found that the larger class 
were in reality rolled plates of iron which seemed to have 
been heavily pressed and torn up from the surface. Another 
and smaller class were less brilliant, and when looked at with 
a considerable power shewed many inequalities of surface 
which would be interesting to study. Probably these were 
the particles which were not torn up but rubbed off. The 
dust enters the mouth and lungs, and has to be taken 
as one of the evils of railway travelling, although we do 
not know that these small particles are worse than those 
of sand. At any rate, it is clear that some kind of iron will 
wear down more readily than others, and we ought to have 
that which will wear down least. By observing what takes 
place in the carriages on a dusty day, every man may to some 
extent compare the iron of different railways. Those which 
give off the largest pieces in greatest quantities, are to that 
extent the worst, as regards health. 
