472 Scientific Intelligence. [Dec. 
mable air were to enter, there is little or no probability that it would 
be inflamed. He referred to the experiments of Grotthus, as 
proving that mixtures of inflammable gases with atmospheric air, 
or even with oxygen gas, cannot be inflamed if they are in a certain 
degree of rarefaction: and he quoted the observations of Dr, 
Thomson, that the exploding power of carbureted hydrogen is not 
considerable, that a certain proportion of it with atmospheric air is 
necessary to enable it to inflame, and that no mixture of fire-damp 
with atmospheric air can be made to explode out of the mine. In 
the small quantity, therefore, in which it must be within the lamp, 
in its areted state from the heat, and with a diluted atmosphere, 
there is no probability whatever that it would be inflamed: and by 
properly adjusting the size of the aperture, this might even be car- 
ried so far that, instead of inflaming, it would weaken or extin- 
guish, the flame; and still more, if ever inflammation or detona- 
tion should take place within the lamp, there would be no chance of 
this being communicated to the air of the mine. If, notwithstand- 
ing all these means of security, danger should be dreaded in any 
particular situation, it might be effectually guarded against by con- 
veying pure air from the bottom of the shaft through an iron tube, 
which by upright tubes might communicate both with the fixed and 
moveable lamps. This, however, would probably be seldom neces- 
sary. 
The accumulation of the fire-damp, when it occurred, ‘would be 
indicated by its smell, or by its effect on respiration ; and if it ever 
proceeded to that extent, by its effect in weakening the flame of the 
lamp; and when suspected, could be easily ascertained by more 
accurate trials. Its discharge can be effected by opening a more 
perfect ventilation, or by the application of a steam-engine, or an 
exhausting machine. 
This method Dr. M. suggested might even be applied with safety 
so as to light the mines with great economy and advantage by coal 
gas. The same method admits also of being used with equal effect 
toguard against choak-damp, the other deleterious gas which occurs 
in mines and other situations. His paper will be speedily published. 
ee 
+, * The author of the paper on the “ Relation between the Specific Gravity of 
Gaseous Bodies and the Weight of their Atoms” thinks it proper to state, that 
many of the numbers in the fourth table in that paper, which are slated to be 
given on the authority of Berzelius, will be found to differ from those given by 
that chemist in the Annals, v. iii. p. 362, on account of their having been founded 
on the deductions of others, (principally of Dr. Thomson) from the experiments 
of Berzelius, and not upon that chemist’s own deductions, 
—= 
+4 + The following note by Dr. Henry arrived too late to be inserted in that part 
of his paper where he speaks of Mr, Parkes:— , 
“ Tt is but justice to Mr, Parkes to state, that 1 am far from suspecting him of 
the intentional suppression of any fact respecting the history of the new method of 
bleaching; and that I believe his account to be a faithful one, so far as his means 
of information extended.” , 
