368 Mr. Moyle on the Atmosphere of the Cornish Mines. 



Sample 18. Four gallons. 



Consols. — As before. Sample obtained under similar circum- 

 stances to the last ; specific gravity *997. 



Oxygen. 

 Average of three experiments with hydrogen . . . 18-41 

 Average of three experiments with quadrisulphuret \ c , 



ot lime J 



Average of two experiments with nitrous gas . . . 18-45 



Mean . . . 18-425 

 Carb. acid. 

 Average of three experiments with lime water . . . 0*06 

 Average of two experiments with potash solution . . - 07 



Mean . . . 0-065 

 Composition of sample : — 



Nitrogen 81*52 per cent. 



Oxygen 18*42 



Carbonic acid . . . 0*06 



100-00 

 Summary of foregoing experiments: — 



Average quantity of oxygen per cent 1 7*067 



Average quantity of carbonic acid 0*085 



Average quantity of nitrogen 82*848 



100*000 

 The results of the foregoing experiments clearly demon- 

 strate the impure state of the atmosphere which a miner is 

 compelled to breathe for about one-third of the period of his 

 existence (generally eight hours at a time out ofcthe twenty- 

 four). There cannot be a doubt, that where much gunpowder 

 is used often pernicious gases are generated, the detection of 

 which will not be easy in samples taken with water, as I have 

 failed in almost every instance in finding a trace of such, by the 

 nicest tests. That sulphurous acid is produced, there cannot 

 be question, as it may be found invariably in the water pre- 

 served in the jars, when the samples have been taken im- 

 mediately after the explosion of a hole, as well as in the air 

 well preserved in a bottle by mercury, and very speedily ex- 

 perimented on in a mercurial trough. 



The minutiae of preparing the different tests, and the pre- 

 cautions adopted in the foregoing experiments, are fully de- 

 tailed in the above-mentioned Transactions, and it is therefore 

 considered unnecessary to recapitulate them here. 



