PREVENTION AND EXTINGUISHMENT OF FIRES. 153 



were made, one of prepared wood and the other of unprepared wood. 

 These were then saturated with paraffine and ignited. In the case of the 

 prepared wood the paraffine soon burned itself out without communicating 

 the flames to the wood, which was only slightly charred. The other heap 

 burned fiercely, and in half an hour was reduced to ashes. The next ex- 

 periment was made with two wooden huts, one of which had been prepared, 

 while the other, built of ordinary Scotch fir, had not. A strong fire, suf- 

 ficient to ignite the houses, was made in each, and the effect was the same 

 as in the previous experiment. A chest containing a parchment document, 

 was treated by the process and was thrown into the flames when at their 

 height, and was taken out sometime afterwards, charred indeed on the out- 

 side, but uninjured in every other respect. The inside was quite cool, and 

 the wax seals on the document were intact. Perhaps the most important 

 trial was that which took place with gunpowder. A government keg, which 

 had been rendered fire-proof, was used. A paper packet containing twO' 

 ounces of gunpowder was put in the bottom of the keg, and a sheet of 

 brown paper impregnated with the tungstate was pasted over it and dried. 

 The keg, which was open at the top, was turned upside down and surround- 

 ed by shavings, which were lighted. A fire of petroleum and shavings was 

 kept burning on the top fifteen minutes without producing the slightest ef- 

 fect on the keg. To make the trial still more complete, the keg was re- 

 versed again, and lighted shavings were thrown upon the gunpowder pro- 

 tected only by a sheet of brown paper. The paper stood the test admir- 

 ably, and the solution rejected the fire so thoroughly that the paper did not 

 show even a sign of charring. The gunpowder was then taken out aad ex- 

 ploded." 



Messrs. Moore & Weatherby, of England, have adopted a plan for the 

 impregnation of wood with a fire-proof solution, which combines with the 

 mechanical processes above described, a chemical action involving the forma- 

 tion of the desired salt within the structure of the wood. After kiln-dry- 

 ing the lumber to be acted upon, they put it into suitable cylinders where 

 lime and water with sulphurous acid gas are forced into the pores of the 

 wood under considerable pressure, the theory being that when sulphurous, 

 acid is passed into lime under pressure a sulphite of lime is formed which is 

 soluble in water, capable of crystalizing into a bi-sulphite, which is readily 

 oxidizable and convertible into sulphate of lime or gypsum. 



Most of the sulphates are to be regarded as incombustible, owing to their 

 firmly resisting oxidation, but sulphate of lime being probably the cheapest 

 and best non-conductor of the heat of any of them, is most used by manu- 

 facturers of fire-proof safes and for similar purposes, and hence the effort of 

 Messrs. Moore & Weatherby to produce it. Of course their process is too 

 expensive to be applicable to ordinary building materials; but since the- 

 kiln-drying is only requisite for driving off the turpentine and other volatile 

 and inflammable oils, I am not sure that it may not be dispensed with in. 

 preparing many of the loose-grained and non-resinous woods used for build- 



