Nature and Physiological Action of Black-damp. 249 



January 24, 1895. 



Sir JOHN EVANS, K.C.B., D.C.L., LL.D., Vice -President and 

 Treasurer, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The Right Hon. Horace, Lord Davey, a member of Her Majesty's 

 Most Honourable Privy Council, was balloted for and elected a 

 Fellow of the Society. 



A 



The following Papers were read : 



I. " Notes of an Enquiry into the Nature and Physiological 

 Action of Black-damp, as met with in Podmore Colliery, 

 Staffordshire, and Lilleshall Colliery, Shropshire." By JOHN 

 HALDANE, M.A., M.D., Lecturer in Physiology, University 

 of Oxford. Communicated by Professor BuRDON SANDER- 

 SON, F.R.S. Received December 6, 1894. 



Black-damp, sometimes also called choke-damp, or " stythe," is one 

 of the gases frequently found in the workings of coal mines. It is 

 distinguished from fire-damp by the fact that it is not explosive 

 when mixed with air, but extinguishes flame; and from after-damp 

 by the fact that it is not the product of an explosion, but collects in 

 the workings under ordinary conditions. Like after-damp and fire- 

 damp, it produces fatal effects when inhaled in sufficient concentra- 

 tion. A further distinction has been drawn between black-damp and 

 white-damp, which latter is described as capable of supporting com- 

 bustion, while at the same time acting as a poison when inhaled. 



Black-damp usually occurs in old workings and other ill-ventilated 

 parts of coal mines. It is much more common in some districts than in 

 others. As to its composition, very little seems to have been hitherto 

 ascertained, and I have not been able to discover any published 

 analysis. The prevailing opinion, however, is that it consists of 

 carbonic acid, and that its suffocative properties are due to this gas.* 

 This opinion appears to be chiefly based on the observation thac 

 black-damp frequently lies along the floors of workings with fresh 

 air above it, and must therefore be, like carbonic acid, heavier than 

 air. 



* See, for instance, minutes of evidence before the " Royal Commission on 

 Accidents in Mines," Nos. 46, 768, 6930, 11702-3, 11707-14. 



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