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168 B. N. A. BOUNDARY COMMISSION. ie | 
the spontaneous fire was in activity. The Indians say that as long ¢ 
they can remember this has been the case.’’”* aay 
393. This combustion, though often spoken of as spontaneous, — 
cannot, I think, be proved to be so. In cases of the spontaneous com- 
bustion of bituminous coal, which sometimes occur when large masses — a 
of it are piled together, the production of the degree of heat necessary 
for its initiation, is traceable to the decomposition of pyrites, under > mt 
~~ 
the combined action of air and moisture. In my Report of Progress ‘ ‘a a 

a ' ignition of the beds by prairie fires, or fires of Indians’ or Traders’ gh if 
camps; or by the spontaneous combustion of the lignite, when un-  _ 
‘" dergoing decomposition at the outcrop. The latter, however, seems 
b improbable, as iron pyrites, the usual cause of such spontaneous 
combustion, is almost entirely absent from the lignites, which I have 
examined chemically.” To this I can now only add, that a further 
examination of the lignites, over a more extended area, confirms the 
almost total absence of visible pyrites, and the very small quantities of 
iron found in the ashes, would alone serve to prove its non-existence in 
any quantity. The only clear case of the occurrence of pyrites, is in the 
lower part of the 18-foot bed on Porcupine Creek, where small dises of the 
material, about the thickness of ordinary paper, were found in the vertical 
joints. Mr. Marvine also, in speaking of the lignites of the same for- 
mation in a more southern region, remarks that the sulpher seldom 
reaches one per cent., and is often nominally absent. + Though it is 
chemically possible, that spontaneous combustion might arise, under 
certain circumstances, in the carbonaceous matter of the soft, crumbled 
outcrops of the lignites themselves; it is obvious that such places would 
; offer the most favourable opportunities for the ignition of the beds by 
prairie fires. These, even when burning over very scantily grassed 
regions, possess sufficient heat to ignite the bois des vaches, or dried 
buffalo excrement, with which the surface is strewn,—a much less com- _ 
bustible fuel. Mr. Allen says that several instances are well known of 
the lignite beds having taken fire from the burning of the prairie grass 
| by the Indians. It would therefore seem that the aid of spontaneous 
combustion need hardly be invoked. { 
394. The destruction by this agency, over great areas, of lignite beds 

* Exploration of British North America, p. 88. +t U. S. Geol. Surv. Territ., 1873., p. 110. 
t It should be mentioned, however, that such good authorities as Profs. Lesquereux and Meek refer 
to the spontaneous combustion of lignite slack, at Carbon and Coalville respectively. U.S. Geol, Surv. 
Territ., 1872, pp. 368, 449, 
