SPONTANEOUS SUBSTANCES. 



produced, when oil of turpentine was substituted for the hemp or 

 rape. oil. In general it was found, that the accension took place 

 more readily with the coarser and more unctuous fir-black, than 

 with the finer sorts ; but the proportions of the black to the oil did 

 not appear to be of any great moment. Sometimes, in wet wea- 

 ther, these mixtures only become hot for some hours, and UK n 

 cooled again, without actually taking fire. 



In all these cases the soot or black was from wood, and not 

 coal. The presence of lamp-black, or any other dry carbonaceous 

 matter, is not necessary however ; for a spontaneous inflammation 

 will take place in hemp or cotton, simply soaked in any of these 

 expressed oils, when in considerable quantity, or under circum- 

 stances favourable to this process, as in very hot weather, or 

 closely shut up. An accident of this sort happened at Gainsbo- 

 rough, in Lincolnshire, in July, 1794, with a tale of yarn of 

 1201b., accidentally soaked in rape-oil; which, after remaining in 

 a warehouse for several days, began to smoke, to emit a most 

 nauseous smell, and finally to burst out in a most violent flame. 

 A similar accident, with a very small quantity of the materials, 

 happened at Bombay. A bottle of linseed oil had been left stand, 

 ing on a chest; this had been thrown down by accident in the 

 night, the oil ran into a chest which contained some coarse cotton 

 cloth, and in the morning the cloth was found scorching hot, and 

 reduced nearly to tinder, and the wood of the chest charred on 

 the inside. On subsequent trial, a piece of the same cloth was 

 soaked in- oil, shut up in a box, and in no longer time than three 

 hours it was found scorching hot, and on opening the cloth it burst 

 into fire. Similar to tin's is the spontaneous combustion of wool, 

 or woollen yarn, which has occasionally happened when large 

 quantities have been kept, heaped up in rooms little aired, and in 

 hot weather. The oil with which wool is dressed, which is gene- 

 rally rape. oil, appears the chief agent in this combustion. Even 

 high dried, oily, or farinaceous matter of any kind, will alone 

 take fire, when placed in circumstances very favourable to this 

 process. Rye flour roasted till half parched, and of the colour of 

 coffee, and wrapped up in a linen cloth, has been found to heat 

 violently, and to destroy the cloth. Wheat flour, when heated in 

 large quantities, and highly dried, has been known to take fire in 

 hot weather, causing accidents in granaries ;iud bakers' shops. An 

 accident of this kiud is related by Count Morrozzo, in the Memoirs 



