66 Repokt 8. a. a. Advan^-kaient of Scikxcu. 



Before each experiment a sample of the air of the drive itself was 

 taken at a certain spot, and when the blast was finished the vitiated air 

 was sampled at the same spot. Sometimes circumstances rendered 

 this impossible, but I shall not deal with the exceptions. Then, again, 

 I have already referred to the influence of the fuse on the vitiation of 

 the atmosphere, and to determine this the usual amount of fuse was 

 burned and the mine air sampled before and afterwards. 



I shall deal first of all with the ordinary )nine air, aiid select 

 the following three as typical examples : — 



A very elementary knowledge of h3'^giene shows tjiat all tluee are 

 very bad indeed, but it must be remembered that a drive is not the 

 best ventilated part of a mine. The carbonic acid, as I have already 

 said, does little harm per xe, but its presence in such large quantities 

 indicates bad ventilation, and as a matter of fact this is the only 

 deduction which is ever made from a carbonic acid test. It is a very 

 different matter, however, with the carbon monoxide. Most of the 

 authorities are agreed that a prolonged stay in an atmosphere wliich 

 contains even the above ((uan titles must have very bad effects on the 

 liealth. 8ome of the samples showed even larger (piantities. 



I pass on now to the composition of the gases after a blast, and 

 again I select three typical examples. All samples were taken as 

 neai'ly as possible under the same conditions : — 



I. IT. III. 



Carbon monoxide ... -93 per cent. 1^28 per cent. •OS per cent. 

 Carbonic acid ... 6-92 ,, 7-96 ,, 7-14 ,, 



These figures tell their own tale, and comment is almost unnecessary. 

 The carbonic acid, if present alone, would cause asphyxiation, but the 

 carbon monoxide would cause almost instantaneous death. To me 

 tliese figures have been a revelation, and few Qxen at this time of day 

 would be prepared to accept them, but dozens of experiments cari'ied 

 <jut on similar lines, and with every precauti<:»n to eliminate analytical 

 errors, all point the same wa}'. 



Needless to say, miners never intentionally, as a matter <)f 

 fact, enter an atmosphere of the ctjmposition I have just given, but 

 they sometimes do so by accident, aiid the post moi-tem is invariably 

 "death by gassing." 



To my )nind the lemoval of carbon monoxide Ijy efiicient means 

 of ventilation is the most pressing prol)lem which Rand mining engineers 

 have to face, and once its importance is realised and effective measures 

 are taken to deal with it, the healtli of the miners will be vei-y greatly 

 improved. 



