[ 134 3 

 healthy perfon, 19 years old, and 

 found one meafure of it and one of 

 nitrous air to occupy 1.84; which 

 convinced me that the air evaporat- 

 ing from the fkin of young people 

 is not purer than that emitted from 

 the fkin of people more advanced 

 in years ; and that if there mould 

 be any advantage for old people to 

 ileep in the fame bed with young 

 ones, as fome imagine, it cannot 

 likely be owing to their perfpiring 

 a better and wholefomer air from 

 their fkin. It is a very erroneous 

 opinion, and even tending to do 

 material mil chief, that the air of a 

 room, in which a great number of 

 young people have been fliut up, 

 as in fchools, is become very whole- 

 fome for old people to breathe in. 

 I have feen fchool- mailers fo ftrong- 

 ly prejudiced with this notion, that 

 6 they 



