44 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



oxygen present, for an increase of COj displaces a certain per- 

 centage of oxygen; from 5 to 14 per cent, of C0$ is said to 

 extinguish a candle flame, and 58 per cent, will put out a 

 hydrogen flame. A man at work will produce 2.10 cubic ft. 

 CO $ per hour. Choke damp, due to the oxidation of coal, may 

 continue to be given off long after any fire damp has been 

 drained away. It may also be formed by underground fires 

 with free access of air. Its presence is generally determined 

 by the failure of lights to burn well ; it may also be tested by 

 aspirating air through lime or baryta water. 



Carbon dioxide being incapable of supporting life is irre- 

 spirable, the arterial blood rapidly becomes venous; besides, 

 it is in itself a narcotic poison. A man who finds himself in an 

 atmosphere containing too much C0 breathes deeper and 

 more frequently, the slightest exertion causes panting, he gets 

 a headache with great pressure in the temples, becomes giddy, 

 drowsy, loses muscular power ; there is profuse perspiration and 

 nausea, singing in the ears and a pungent sensation in the 

 nose, and finally insensibility, culminating in death, if the 

 sufferer is not removed and resuscitated. It must be noted 

 that death need not result, even though a man has been un- 

 conscious for some time, if he is removed to fresh air and arti- 

 ficial respiration be resorted to. 



Carbon monoxide (CO) or "white damp," is a very in- 

 sidious poison. Its presence in collieries is due to incomplete 

 combustion during fires or explosions. It has a sweet, deli- 

 cate odor : it does not extinguish lamps as it is inflammable, 

 but it is not explosive until the proportion of CO is over 15 

 per cent. 



Under ordinary conditions of breathing the oxygen of the 

 air is absorbed by the blood and forms an unstable chemi- 

 cal compound with the red colouring matter (haemo- 

 globin) of the corpuscles, which is utilised by the 

 body. Carbon monoxide is poisonous, its poisonous 

 character being due to its chemical avidity for hemo- 

 globin, which is stated to be 200 to 250 times greater 

 than that of oxygen. As soon as the blood is saturated with 

 CO, which forms carboxy-hsenioglobiii, and is very stable, it 

 ceases to take up any further oxygen from the air. Experiment 

 shows that only 60 per cent, of inhaled CO is actually absorbed 

 by the blood. Bad symptoms are produced where only 0.05 

 per cent, is present in the air, while death results with from 

 Q.3 to 1 per cent. When CO accumulates in the blood to 30 

 per cent., it causes giddiness, swelling of the veins of the 

 forehead, palpitation, shortness of breath and weakness of 

 sight. At about 50 per cent, a man begins to lose power over 

 his legs, he becomes unconscious, and at 79 per cent, death 

 occurs. As helplessness comes before unconsciousness, a suf- 





