EXPERIMENTS WITH AIR FURNACES. 231 



it was proved that, in the imperfect combustion 

 which takes place in furnaces, this dangerous agent 

 is largely in excess of all other products. Sulphur- 

 ous acid was present whenever a new supply of 

 fuel was added to the fire, and usually when any 

 interference was had with the furnaces. The shak- 

 ing of the contents of the fire-pot by means of the 

 grate-handles invariably caused the ascent into the 

 room of much fine dust and ashes, mingled with the 

 air current. This impalpable dust is not usually 

 noticed by the occupants of rooms where furnaces 

 are used. It is only when, through very imperfect 

 and leaky joints, large amounts of ashes, and even 

 cinders, are allowed to escape, that many families 

 complain. It is astonishing how negligent or in- 

 different most housekeepers are to the presence of 

 agents destructive to comfort and health. We 

 have been informed by a very extensive manufac- 

 turer and dealer in house-warming apparatus, that 

 in one hundred furnaces which came under his 

 observation for repairs, more than three-fourths 

 had the air chambers and passages obstructed by 

 coal ashes. It was no unusual circumstance to re- 

 move a bushel from some chambers through which 

 the heated air passed to the rooms of the dwellings. 

 What an unhealthy, deleterious mixture of air and 

 ashes must here be produced for children and adults 

 to breathe ! From investigation, we believe there 



