Conflagration of the Odeon, 30 7 



able, if the wood happens to be refinous, or if it be found to contain oih for the fire partly 

 converts them into inflammable air, which immediately, on the accefs of the atmofpheric 

 air, becomes inflamed, and cannot be extinguiflied by water, which only f rves to extend 

 and dire6l the flames. Hence it happens that water can have no efFedl on fuch a conflagra- 

 tion, till the wood becomes converted into charcoal. 



It is faid that the fire of the Odeon (at Paris) was firft difcovered in a room near the cur- 

 tain of the theatre, where it communicated to the decorations and deal frames which fupport 

 them. The great quantity of air which was contained in the hall of ;he Odeon ferved, for a con- 

 fiderable time, to maintain the fire which had decompofed a confiderable part of the wood and 

 oil with which it was incorporated, and reduced itfeli into fmoke and inflammable air, which 

 entirely filled the hall. As foon as the atmofpheric air was introduced it mixed with the in- 

 flammable gas, and exploded. At that inftant the roof of the Odeon fell in, and the flames 

 bur ft forth in all parts at once, becaufe the inflammable air occupied the whole capacity of 

 the hall. 



The fulphur, which continued to burn in feveral parts of the Odeon three days after the 

 fire, gave rife to a notion that the fire had been caufed by malevolent incendiaries. I was 

 myfclf greatly furprized at the quantity of fulphur which I faw in different parts; but, on exa- 

 mining it attentively, I difcovered that it was perceivable only where there had been a great 

 number of laths, timber, and burnt plafter, as in the corridors, the front of tne periftyle of 

 the Odeon, which formed four ftories, and near the fituation of the two ftaircafes of wood 

 which were eredled near the middle of the hall. 



I obferved that the fulphur fublimed into a yellow duft, and that fome fcoriae had cryftal- 

 lized ; but the greateft quantity appeared to be in the ftate of calcareous liver of fulphur, 

 blueifh, friable, which took fire with decrepitation as foon as it came in contaft with the air. 

 Italfo emitted the fiiiell of decompofed liver of fulphur; which confirmed me in the opinion 

 that it was calcareous pyrophore, formed by the decompofition of plafter, which (as is well 

 known) is itfelf compofed of fulphuric acid combined with calcareous earth. This acid, by 

 the afliftance of the heat, united with the inflammable principle of the charcoal, and formed 

 the fulphur which was found in the ftate oi pyrophorus or carbonated calcareous liver of ful- 

 phur in the remains of the fire of the Odeon. 



I fhewed, about twenty years ago, that the pyrophore afforded by the coal of turf is ow- 

 ing to a portion of felenite or plafter-ftone contained in the turfs of France. During the 

 carbonization of thefe turfs, the fulphuric acid of the felenite *, combining with the inflam- 

 mable principle of the coal of the turf, forms fulphur and a calcareous pyrophore. 



On vifiting the ruins of the Odeon, 1 found Monette, the architedt of the department and 

 of the Central Bureau, who informed me, that he had obferved, in the ruins of two different 

 theatres deftroyed by fire, the fame fmell of the liver of fulphur, and the fame eiFeds as took 

 place At the Odeon. 



* The rtader may ptrceive that M. Sage does not follow the new fyftern of chemiilry. 



• This 



