350 THE POPULAR SCIENCE MONTHLY. 



tant researches on this subject, and has shown that, even if the dust of 

 coal is not directly inflammable, it becomes very combustible when the 

 atmosphere contains traces of carburetted hydrogen. Other dusts are 

 directly combustible, and sometimes produce genuine catastrophes by 

 the fact of their suspension in the air. In 1869 a sack of starch was 

 accidentally thrown down from the top of a staircase in the Rue de la 

 Verrerie, Paris ; it burst and scattered through the air a cloud of dust 

 which took fire from the contact with a gaslight at the bottom of the 

 stairs, and caused an explosion. M. Berthelot has observed that spe- 

 cial conditions of mixture are required for the actual production of 

 such explosions, and that a hundred cubic metres of air, containing 

 about thirty kilogrammes of oxygen, will completely burn twenty- 

 seven kilogrammes of starch-powder, or eleven kilogrammes of coal- 

 dust. The terrible explosion in the flour-mills at Minneapolis, Minne- 

 sota, in May, 1878, was of a similar nature with the explosion of the 

 starch in the Rue de la Verrerie. 







THE FOSSIL MAN. 



By HENEY W. HAYNES. 



PREHISTORIC Archaeology, the latest-born of the sciences, like 

 her elder sister Geology, has lived through the successive stages 

 of scornful denial, doubt, and unwilling assent, and has finally won 

 for herself substantial recognition. The " antiquity of man " is now 

 an established fact. Even its most strenuous opponents are forced to 

 concede that there are proofs of his existence during a lapse of time 

 far exceeding the limits of the previously approved chronology. For 

 somewhat of the suspicion with which this result has been received, 

 certain of its advocates may have themselves to blame. "Where abso- 

 lute chronological determinations were of necessity impossible, and 

 where, even at the present stage of the investigation, only general 

 approximations can be reached, it was at least injudicious to startle 

 received opinions, and to arouse prejudices, by asserting for mankind 

 an antiquity of hundreds of thousands of years. Moreover, the great 

 name of Cuvier was held up as a barrier in the path of those who 

 claimed to have discovered proofs of man's existence under geological 

 conditions differing from the present. Cuvier, however, never denied 

 the possibility of finding " the fossil man " ; he only questioned the 

 sufficiency of the evidence of his existence which had been brought 

 under his notice, and with great reason, in view of the numerous in- 

 stances in which pretended fossil human bones had turned out to be 

 those of animals, or even merely natural formations. 



Many have been the definitions given of the term "fossil"; but 



