156 PREVENTION AND EXTINGUISHMENT OF FIRES. 



it. There are several so-called composition roofs, which, in my opinion, are 

 better protectors against fire than metal, because of their superior non-con- 

 ducting properties. 



Wooden cornices are the most dangerous of all fire traps, and should be 

 prohibited in all cities. 



Metalic shutters are of the greatest value when closed, but, being usually 

 forgotten until it is too late to close them, they should be so constructed as 

 to shut automatically at the approach of danger. One means proposed for 

 afi'ecting this is to provide them with springs which will force them shut 

 upon the melting of 'the fusible metal fastenings with which they are to be 

 held open ; but as these springs might from long disuse lose their 

 elasticity, or the hinges their mobility, it might be an improvement to have 

 these shutters suspended above the windows by means of catches of fusible 

 metal or some inflammable material. They would then drop of their own 

 weight when the catches were melted or burned by the approaching flames, 

 and be much more likely to assume their proper places than under the cir- 

 cumstances first named. 



YI. Before closing this branch of the subject it may be well briefly to 

 consider the subject of spontaneous combustion, so far as it bears upon that 

 of the j)revention of conflagrations. That certain substances under cer- 

 tain circumstances will ignite without the application of fire or other ob- 

 vious cause, is a fact too well established to require proof, but in this con- 

 nection I shall only have time to point out a few sets of circumstances un- 

 der which such spontaneous combustion has occurred, and against which 

 we should guard in our dwellings and places of business : 



1. Common soft coal containing a considerable proportion of sulphuret 

 of iron (iron pyrites), a very common impurity in all the bituminous coals 

 of this region, is very liable to ignite spontaneously, especially when wet, 

 which demonstrates the danger to be apprehended from the very common 

 practice of sprinkling water upon the coal in our bins and cellars to lay the 

 dust. 



2. Matches, when kept in considerable quantities together, are liable to 

 ignite spontaneously, owing to the inflammability and oxidability of the 

 phosphorus contained in them. 



3. Solar heat acting upon the bisulphide of carbon, used in all India rub- 

 ber fuctories, has been known to produce it. Also it has occurred in ware- 

 houses where rubber blankets and clotbing were stored. So well known is 

 this fact, that during the late war orders were issued respecting the separate 

 storage of such supplies. 



4. lifitric or sulphuric acid thrown carelessly around upon refuse straw, 

 wool or other litter, will frequently ignite them. 



5. Cotton rags or almost any other waste saturated with oil, used in lu- 

 bricating and wiping machinery, have the property of spontaneous combus- 

 tion in a remarkable degree and have frequently produced serious confla- 

 grations by taking fire in this manner. 



