148 PREVENTION AND EXTINGUISHMENT OF FIRES. 



Combustion is defined. to be "the rapid and violent oxidation of carbon 

 and hydrogen by the aid of the free oxygen of the atmosphere," i. e. all 

 ordinary combustion is dependent upon the presence of oxygen, and cannot 

 continue in its absence. 



I, The first practical inference then that we draw is to so construct our 

 buildings as to prevent the free admission and passage of atmospheric air, 

 which contains so large a proportion of oxygen, to and through those inac- 

 cessible portions, such as the spaces under floors and within partitions, where 

 fires so frequently originate and whence they spread so rapidly. Almost 

 every person present will recall one or more instances where a destructive 

 fire originated in or was caused by the ignition of the base-board of a room 

 from to the too great proximity of a red-hot stove, the immediate extension 

 of the flames within the lath and plaster partition and their rapid spread 

 throughout the building by means of the upward draught of air between 

 the studding. JS'ow, had the partitions in such cases been of brick, or even 

 lath and plaster rendered solid in any way, the draught could not have ex- 

 isted and the flames would have had no tendency whatever to pass within 

 the partition. While this will be the case no matter what materials may be 

 selected for solidifying purposes, manifestly it will be better to choose those 

 that are least combustible and cheapest ; and I know of none cheaper, more 

 effectual and more readily and easily applied than the very same lime and 

 sand mortar which constitutes the first coat of plastering upon such parti- 

 tions. (So far lime has been found to resist all degrees of heat, not even 

 being volatilized or fused in the hottest blast furnaces, while sand is almost 

 equall}^ incombustible). In an ordinary six inch lath and plaster partition, 

 the studding commonly used is two inches by four, set with the four inch 

 side transversely to the line of the wall. The plasterer, in putting on the 

 mortar, forces it through the interstices of the lath from half to three quar- 

 ters of an inch on both sides, thus leaving a space of from two and one-half 

 to three inches wide between these keys, as they are called, which gives free 

 passage for the air and flames as before described. Suppose in constructing 

 such partitions, the studding pieces were turned the other way, i. e., with 

 the two-inch side transverse to the line of the wall, then the space between 

 the keys of the mortar would be but from half an inch to one inch in 

 width, which could be very cheaply and easily filled by the plasterer as he 

 progressed with his work, and the pai-tition thus rendered solid, impervious 

 to air and flame, not less substantial than before, not enough heavier to do 

 any harm, far less communicative of sound from room to room, and lastly, 

 permanently obstructive to the passage of vermin of all kinds. 



Similarly, the spaces between the floors and ceilings of different rooms 

 could be filled with some cheap material, the more incombustible the better, 

 which would serve the purpose of obstructing the spread of fire, at the 

 same time that it performed the very useful functions of deadening sound 

 and preventing such spaces being used as harbors and thoroughfares for 

 rats and mice. In the Itulian and French cities this principle is carefully 



