ogt. — dec. 1857.] Mode of protecting Timber from Fire. 133 

 Experiment 4. 



In order to have convincing proof of the advantages of the pre- 

 paration in retarding the ignition of wood, it was resolved to make 

 experiments, similar to those described as Nos. 1 and 2 ; to observe 

 the difference in time required for the ignition of the wood in the 

 unprepared corners of the hut, and to ascertain the comparative 

 power of the fire to extend, in these parts. 



A fire was kindled in the stove placed in one of the unprotected 

 corners of the hut. In about ten minutes after the stove had be- 

 come thoroughly heated, the sides of the hut burst into flames, 

 which at once rose to the roofing above, and kindled portions of it. 



A heap of wood and shavings was lighted in the opposite un- 

 prepared corner, and in two or three minutes this portion of the 

 hut was in flames. 



The unprepared wood having been once kindled, the fire spread 

 so rapidly as to be quite unmanageable in a few minutes, the 

 flames completely filling the interior of the hut. But even under 

 these circumstances, when the intense heat and fierce flames from 

 the burning portions soon spread the fire to the prepared parts of 

 the hut, it was remarkable how the flame crept along between the 

 crevices and overlapping portions of the planks where the wood 

 was unprepared, so that the prepared surfaces were always tho- 

 roughly surrounded by flame for a considerable time before they 

 ignited, Some portions of the prepared planking, of which the 

 wood had probably imbibed a rather larger quantity of silicate, in 

 consequence of its greater porosity, offered great resistance to the 

 fire to the very last. 



We consider the experiments above detailed to have afforded 

 conclusive proof on a practical scale, of the considerable power 

 possessed by silicate of soda, applied simply as a coating, in con- 

 junction with lime, of retarding the inflammability of wood. 



It is, of course, impossible even by the thorough impregnation 

 of wood with various substances, to deprive it of the property of 

 burning ; the only results to be attained by the use of a protective 

 material are,— 



