SPONTANEOUS SUBSTANCES. 129 



that many vegetable substances, highly dried and heaped together, 

 will heat, scorch, and at last burn into dame. Of these the moat 

 remarkable is a mixture of the expressed oil of the farinaceous 

 feed;), as rape or linseed oil, with almost any other dry vegetable 

 fibre, such as hemp, cotton, matting, &c. and still more, if also 

 united with lamp. black, or any carbonaceous subsianco. These 

 mixtures if kept for a time undisturbed, in close bundles, and in a 

 warm temperature, even in small quantities, will often heat, and 

 burn with a mouldering fire for some hours ; and if air be admitted 

 freely, will then burst into flame. To this without doubt may be 

 attributed several accidental conflagrations in storehouses, and 

 places where quantities ef these substances are kept, as has been 

 proved by direct experiments. The most important of these expe- 

 riments were mad* by Mr. George, and a committee of the Koyal 

 Academy at P*itersburgh. in the year 1781, in consequence of the 

 destruction, by fire, of a frigate in the harbour of Cronstadt; 

 the conflagration of a large hemp magazine, in the same place, in 

 the same year; and a slight fire on board another frigate, in the 

 same port, in the following year. 



These accidents led to a very strict examination of the subject, 

 by the Russian government ; when it came out, that at the time of 

 the second accident, several parcels of matting, tied with pack, 

 thread, in which the soot of burnt fir-wood had been mixed with 

 oil, for painting the ship, had been lying some time on the floor of 

 the cabin, whence the fire broke out. In consequence of which, 

 the following experiments were made: forty pounds of fir. wood 

 soot were soaked with about thirty-five pounds of hemp oil var. 

 nish, and the whole was wrapped up in a mat, and put in a close 

 cabin. In about sixteen hours it was observed to give out a smoke, 

 which rapidly increased, and when the door was opened, and the 

 air freely admitted, the whole burst into a flame. Three pounds 

 of fir-black were mixed with five pounds of hemp-oil varnish, and 

 the whole bound up in linen, and shut up in a chest. In sixteen 

 hours it emitted a very nauseous putrid smell and steam ; and two 

 hours afterwards it was actually on fire, and burnt to ashes. la 

 Another experiment, the same occurrences took place, but not till 

 the end of forty-one hours after the mixture had been made ; and 

 in these and many similar experiments, they all succ -cd- d better, 

 and kindled sooner on bright, than on rainy days. Chimney soot 

 used instead of lamp-black did not answer, nor was any ffect 



TOL. VI. K 



