480 Sir Henry Cunynghame [Feb. 19, 



of black damp, or carbonic acid, we have the products of imperfectly 

 combusted coal, that is to say, after-damp, or carbonic oxide, the 

 gas that kills people who commit suicide so often in Paris l^y means 

 of a charcoal brazier. For whenever coal is imperfectly burnt, as in 

 an ill-arranged stove, there not only is carbonic acid formed, but 

 likewise carbonic oxide. 



In ordinary gas as supplied in most large towns there is a con- 

 siderable quantity of carbonic oxide present, so that to sleep in a 

 small room with the unlit gas turned on is usually fatal. 



The effect of carbonic oxide on the human frame is caused by the 

 fact that it is greedily absorbed by the haemoglobin or the red colour- 

 ing matter of the blood corpuscles. 



This renders them incapable of absorbing oxygen from the lungs 

 and carrying it to the various parts of the body in order to burn up 

 the carbon derived from the food. In consequence carbonic oxide is 

 an active poison. 



The poisonous nature of carbonic oxide has, of course, been known 

 for many years, but it was reserved for Dr. Haldane, of Oxford, to 

 demonstrate to the mining world what a part this poisoning plays in 

 coal-mine disasters. I think that I may, to some extent, claim the 

 credit of having first recognised the ability and devotion of Dr. 

 Haldane in this work, and of having secured his services to help in 

 the investigation of mine explosions. 



The period at which the importance of carbonic oxide was most 

 impressed on us was at the Tylerstown explosion, in 1896, at which 

 57 men were killed, o3 being brought out alive. 



Dr. Haldane, in company with Dr. Morris, undertook and carried 

 out the task of examining 45 of the bodies after they were recovered. 

 The object was to discover the cause of death. "When death has been 

 caused by carbonic oxide, the blood of the dead man exhibits charac- 

 teristic symptoms which Dr. Haldane has devised a simple and practical 

 manner of testing. I have his apparatus here, and he has been good 

 enough to say that he will show it in detail after the lecture to anyone 

 who is interested. 



Provided with the apparatus and with the assistance of the 

 inspectors the examination proceeded, and resulted in the classical 

 report of 1896 on the causes of death in colhery explosions and under- 

 ground fires. 



The bodies were covered with an adhering layer of charred coal- 

 dust. But there came the surprising discovery that in only five cases 

 was the death due to the violence of the explosion. In all the other 

 cases death had been due to carbonic oxide, showing that the men 

 must have lived and breathed perhaps for hours after the explosion. 

 Of the rescued men, a number had been rendered unconscious, also 

 by the after-damp. The death is quite a painless one ; the only 

 symptoms are a slight smarting of the eyes and throat, and then, 

 though the lamps are burning well, and there is plenty of air tO' 



