220 ANNUAL OF SCIENTIFIC DISCOVERY. 



small quantity of oil, used as a lubricant, becoming, no doubt, in the 

 first instance ignited, and then imparting the combustion to the iron. 

 The whole interior surface of the iron receiver was blistered and 

 coated with fused globules of magnetic oxyd of iron, the small tubu- 

 lar apertures through the screw-plug were widened to fourfold di- 

 mensions, and no less than half an inch of steel was burnt olF the 

 massive head of the apparatus. It was, perhaps, so far fortunate that 

 a defective joint rendered it impossible to obtain more than the 

 pressure of 25 atmospheres, under which the apparatus exploded ; for 

 had it been augmented to 40 atmospheres, the iron must have taken 

 fire more readily, and perhaps have been completely consumed or hurled 

 about as red-hot bolts, endangering both life and property. Dr. 

 Frankland had, by a rough calculation, arrived at the conclusion that 

 the heat developed by the union of half the contained oxygen with 

 the iron would have been sufficient to melt the cylinder, Avhich would 

 then have exploded by the remaining pressure of the other half of the 

 gas. He concluded by referring to the possibility of applying this 

 principle in the construction of shells, and other implements of war- 

 fare. 



RESEARCHES ON THE INFLUENCE OF CAD AIR. 



In a recent official report to the British Parliament on the state of 

 the Cornwall and other mines by Dr. Angus Smith, particular notice 

 is taken of the influence of impure air in breaking down the healch and 

 energy of the workmen. A healthy atmosphere, says Dr. Smith, may 

 be taken to be one with 20' 9 per cent of oxygen, and -04 per cent 

 of carbonic acid gas. Late in the evening in the pit of London minor 

 theatres as much as O252 and 0*320 per cent of carbonic acid has 

 been found ; but the average of above 300 samples of air taken from 

 the mines examined had 0'78-3. Two thirds of the samples pre- 

 sented an atmosphere exceedingly bad, and the worst parts of the mines 

 had only about 18*69 per cent of oxygen, and as much as 1*8 or 

 more of carbonic acid, in one instance 2*26 per cent.' In order to 

 test the effects of such bad air, Dr. Smith caused to be constructed a 

 small close chamber of lead with windows sufficiently large that they 

 might in any emergency be broken through for a way of escape. The 

 first trial was made by sitting down in the chamber for an hour and 

 40 minutes. This produced about one per cent of carbonic acid, 

 and the air became cheerless. A young lady was anxious to be in the 

 chamber when the air was such that candles would not burn. She was 

 not much struck by the impurity of the air on entering, although the 

 candles were threatening to go out ; there was not quite 19 per cent 

 of oxygen, and there was rather more than two per cent of carbonic 

 acid. Xo one had been breathing in the chamber, so that organic 

 matter from the person was absent and that makes a great difference. 

 She stood five minutes perfectly well, making inrht of the difficulty, 

 but suddenly became white and could not come out without help. On 

 another occasion a still greater amount of carbonic acid was present 

 in the chamber, but it was not accompanied with a corresponding loss 

 of oxygen, for the gas was driven in upon pure air; there was 20*19 

 per cent of oxygen, with 3*84 of carbonic acid. Two persons got 

 headaches instantly, and were unable to stay above seven or eight 



