hi Charcoal in Atmospheric Temperatures. 73 



against each other, and the finer parts would bo shaken to a 

 compact mass ; and possibly the friction might, in this case 

 particularly, produce a degree of boat which might promote 

 the ignition. 



Before I proceed to an account of ray own direct experi- 

 ments, I will describe here another instance of spontaneous 

 combustion which occurred casually. About 2,000lbs. weight 

 of charcoal were loaded at Cornbrook, in the cart of Messrs. 

 Williamson and Co., powder manufacturers, of Fernelee, near 

 Buxton. The charcoal had been made several days before, and 

 had lain freely exposed to the open air. No indications of com- 

 bustion could be perceived. After being taken oui of the cart 

 at Fernelee, it was left for the night, and the next day finely 

 pulverised as a preparation for making gunpowder. It was then 

 thrown into a heap ; and no appearance of a tendency to ignite 

 ensued. This was on the Saturday evening ; and on Sunday 

 the building which contained it was observed to be on fire. The 

 fire must have commenced with the charcoal, as every other 

 source of heat Avas carefully excluded, ou account of the 

 gunpowder manufactory. 



These, and a number of other accidents which have arisen 

 from the same cause, united with the opportunities which I 

 have possessed as a manufacturer of charcoal, have led me to 

 take particular interest in the subject. And I therefore came to 

 the determination of making, for my own satisfaction, a few 

 experiments, which I shall proceed to describe. 



Exp. 1. — 120 pounds of charcoal, slightly pulverized, were 

 put into a flour-barrel, and a leaden tube, of an inch and a half 

 in diameter and 14 inches long, inserted in the middle, to hold 

 a thermometer. The temperature of the charcoal when put 

 into the barrel was 60". In two days the charcoal acquired 

 a temperature of 74° ; from that time the temperature gradu- 

 ally diminished until, in two days more, it was reduced again 

 to 60°, — the temperature of the surrounding atmosphere. 

 This charcoal was rather old, having been made several weeks, 

 and afterwards freely exposed to the open air. 



Exp. 2. — 120 pounds of fresh charcoal, pulverized as before, 

 were put into the vessel used in the preceding experiment. 

 The charcoal was then at 70°, and the surrounding air at 62". 

 In 24 hours it had acquired a temperature of 90° ; in 36 hours, 

 of 110° ; and in 48 hours, of 120° : from this time the tempe- 

 rature fell •, and in 48 hours more it was down to 70°, as at the 

 commencement. 



Exp. 3. — The same quantity of charcoal was taken as in the 

 foregoing experiments: it was quite fresh, and ground into 

 coarse powder. In 36 hours the temperature was 130° ; it then 

 gradually declined to 70°, when the experiment was -jiven up. 



K 



