128 



Selections. 



[NO. 5 a NEW SERIES, 



" By the heat of the fire, the salt was drawn to the surface of the 

 wood, and fused, forming a glazing upon it. 



" Subsequently, when the whole building was destroyed by fire, 

 after unsuccessful attempts to extinguish it by means of the " An- 

 nihilators," the fierceness of the flames was such, that few mate- 

 rials could have withstood it : yet, of the exterior coated portion 

 of timber, several planks remained. 



" Upon examining these, the unprotected surfaces which had 

 been directly exposed to the fire were found to be completely char- 

 red, but this charring had extended only to the point to which the 

 silicate had penetrated from the other side of the plank. 



" This experiment is considered to have proved that the silicate 

 of soda is a very valuable protective agent, and that, even when 

 simply applied as a paint, it will serve to protect wood for a consi- 

 derable time from fire, and to retard greatly the spreading of a con- 

 flagration." 



Shortly after the experiments above described were made, the 

 possibility suggested itself of rendering the coating of silicate less 

 destructible by exposure to wet, of increasing its efficiency as a 

 protective, and of rendering its application more economical, by 

 combining with its use that of ordinary lime-wash. 



Some pieces of plank were prepared in the following manner ; 

 a dilute solution of the silicate of soda was first applied with a brush ; 

 when this had thoroughly soaked into the wood, and dried, a thick 

 lime-wash (made by slaking some lime, and reducing the hydrate 

 to a smooth wash of the consistence of thick cream) was applied, 

 and lastly, after the planks had been exposed to the air for two or 

 three hours, they were painted with a second solution of silicate of 

 soda, somewhat stronger than that first used. The effects of the 

 liquids thus applied, both upon the wood and on each other, will be 

 more particularly pointed out in a report subjoined. 



Several experiments, precisely similar to those described below, 

 were made with the prepared planks, the results proving most sa- 

 tisfactorily that the protective coating resisted to a remarkable de- 

 gree the action of heat, evinced no symptom of peeling off the high- 

 ly heated surface of the wood, and protected the fibre to a great 

 degree from the influence of flame playing upon its surface. 



