THE METAMORPHOSES OF MATTER. 115 



frail tenure and instability of these, that the elements per- 

 forming for a time such deadly duty shall soon be more 

 genially employed. Pure prussic acid is so very deadly, that 

 one breath of it into the nostrils extinguishes life in an in- 

 stant ; and one drop of it poured into the eye of a strong 

 dog kills the animal not less suddenly than if his heart had 

 been torn out by a cannon-ball. Now contemplate this : 

 if nitrogen, hydrogen, and carbon had been destined to com- 

 bine naturally, forming prussic acid to any considerable ex- 

 tent, the existence of animated life would not have been 

 possible. If the decomposition of animal bodies be allowed 

 to go on gradually without impediment, as when buried under 

 earth, carbon, hydrogen, and nitrogen do not unite to gene- 

 rate prussic acid; but, let decomposition proceed under the 

 modified circumstance of restraint, as in a lead coffin, then 

 is that deadly compound prussic acid generated, amongst 

 others; a sort of indication that Nature rebels against the 

 monopoly of her elements which human pomp would enjoin. 



A while ago we seemed to have made out that if all the 

 carbon present in all the bodies of animated things now 

 living on the earth could be collected and weighed, it would 

 be seen to amount to the enormous quantity of 24,102,424 

 tons ; presently we will compare it with the bulk of carbon 

 already exhausted from the earth in the form of pit-coal; 

 but prior to this it may not be amiss to contemplate the vast 

 amount of carbon evolved from the lungs of humanity day by 

 day. In the breath that we expire charcoal exists. Though 

 under ordinary circumstances invisible (and well too, or how 

 sooty we should be !) the chemist can make it visible can 

 collect it, weigh it. This done, every adult human being is 

 found on the average to evolve no less than thirteen and a 

 half ounces of charcoal during the tw^enty-four hours, which 

 for 1200 millions of adults would be about 23,000 tons, and 

 which if halved, in consideration of youths, old age, and babies, 

 would still be enormous. 



