164 [December, 1844. 



giving rise to the sulphite of ammonia, one of the known products 

 of the gas making process. 



Reference was made to the first volume of the Proceedings, page 

 140, for an account of another case, not of actual combustion, but 

 of the heating to 110° of a heap of coal from the same coal district; 

 and to an instance which had come under the observation of Prof. 

 Johnson, at Lowell, Massachusetts, where, having found a tem- 

 perature of 160° in a heap of Sidney, Nova Scotia, coal, at a dis- 

 tance of three feet from the surface, a period of 50 days was allowed 

 to elapse, in which time it actually took fire. 



The importance to coal dealers of attending to the character of that 

 which they store and keep on hand for months, was rendered apparent 

 by the occurrence now alluded to. Had the combustion occurred on 

 another side of the heap, ii would have set fire to a coachmaker's shop 

 filled with combustible materials. Had it been on ship-board, the 

 planks and timbers might have been charred, or the vessel set on 

 fire, with scarcely the possibility of extinguishing the flames. The 

 decomposition of sulphuret of iron, found in such abundance in this 

 coal, aided by air and moisture, affords a ready solution of this and 

 similar occurrences. 



Dr. Gibbons exhibited a diagram, intended to show the 

 path of the thermometer as compared with that of the baro- 

 meter, in which the great fluctuations of the former instru- 

 ment are observed to follow those of the latter at a distance 

 of about thirty-six hours. 



Also a table, showing that the mean temperature of the 

 last six days of November, for a period of seventeen years, 

 ending 1843, is lower than that of the first six days of De- 

 cember, by 0°.S7. 





Mr 



