PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 583 



quantity of coal, or pile on wood, which is a very bad plan, and 

 causes actual loss, from the fact that a large percentage of hydro- 

 gen gas is formed, which escapes up the flue without taking fire ; 

 you may always know when this valuable property is going to 

 loss, by holding a lighted paper in the smoke, if hydrogen is es- 

 caping it will ignite. Always so manage your fire that the front 

 portion is red, because your apartments are invariably heated by 

 radiant heat, A good firemaker should be cognizant with the 

 chemical laws of nature. 



Remember that bad coals, though cheap in price, are not by any 

 means economical, because they are not inflammable. 



All fuel should be kept perfectly dry, as when exposed in damp 

 places, much of its material in burning is converted into water 

 and escapes up the flue, carrying with it the heat that was neceiS- 

 sary for its conversion. Unseasoned wood contains at least one- 

 third of its weight of water. 



With regard to the quantity of heat that may be obtained from 

 various substances used as fuel, a comparison may be easily made 

 by melting ice. 



For instance, two lbs. of wood melts 65 lbs. of ice ; two lbs. of 

 coke melts 166 lbs. of ice; two lbs, of hydrogen gas melts 660 

 lbs. of ice; two lbs. of coal melts l75 lbs. of ice; two lbs. of 

 wood charcoal melts 188 lbs. of ice ; two lbs. of tallow melts 204 

 lbs. of ice ; two lbs. of olive oil melts 335 lbs. of ice. 



An interesting discovery has been made in Russia, between 

 Dorpat and Norva, of a combustible as califactory and carbonif- 

 erous as coal. It is of a yellowish color, covered with white 

 spots, and is the subject of speculation among scientific men, from 

 the fact that it is of a much earlier geological period than the 

 coal era. 



Mr. Seely said that it was an error to suppose that charcoal 

 had antiseptic properties. It will not assist in the preservation 

 of meat, or of any animal or vegetable substance. The power 

 which it really has is that of absorbing gases, so that it absorbs 

 the offensive emanations from decomposing meat, and apparently 

 makes them sweeter. 



Mr. Stetson narrated an experiment with fine charcoal, by 

 which meat which had become quite offensive was entirely 

 changed in one night so that it was cooked, and soon eaten up. 



Mr. Pell related an incident with regard to the manufacture of 

 glue. He had proposed the use of charcoal to render inoffensive 



