324 CRITICAL NOTICES OF NEW PUBLICATIONS. 



ers contained very little water, and had suddenly thrown in a plenti- 

 ful supply. 



Doubts as to the development of steam by heated metal have led 

 to the supposition that water is decomposed in an unduly heated 

 boiler, giving rise to the production of hydrogen gas.* We have 

 always considered the attempts to explain explosions in this way as 

 entire failures, from the impossibility of furnishing free oxygen to the 

 hydrogen within the boiler to produce an explosion. The Committee 

 whose labours are under discussion have made an elaborate set of 

 experiments, to ascertain if water is decomposed, as has been assum- 

 ed, when thrown into a red hot boiler. They find that no such de- 

 composition takes place, and thus remove the very foundation of the 

 hypothesis. They admit that carburetted hydrogen does, no doubt, 

 exist at times in a boiler, in greater or less quantities, from the de- 

 composition of oil or of vegetable substances introduced to stop leaks 

 or to prevent deposits ; but consider that there is no warrant for the 

 idea that this gas can accumulate and mix with air within a boiler, so 

 as to become a source of danger. 



They then consider some cases of explosions which have been 

 assumed as produced by hydrogen, particularly one which occurred 

 at Pittsburgh in the United States. A cylindrical boiler was thrown 

 up into the air, and a stream of fire described as issuing from it, 

 by an eye witness of the explosion. This observation they explain 

 by the optical phenomenon always occurring when luminous bodies 

 are viewed in rapid motion. 



Having proved that danger results from heated metal within a 

 boiler, and disposed of various hypotheses connected with this fact of 

 the subject, the Committee proceed to examine the probable causes 

 which may lead to this source of danger, and the remedies which have 

 been suggested to meet them. 



The causes examined are : first, a deficient supply of water within 

 a boiler ; second, the existence of deposits from the water used to 

 supply the boiler, or from other sources ; third, in the particular 

 arrangement of contiguous and communicating boilers on board of 

 steam boats, by the deck of the boat being inclined to the horizon. 



In all these cases it is necessary to shew, not merely that heated 

 metal will result, but that water can get access to it ; otherwise no 

 dangerous effects follow. In the first case, besides the ordinary cir- 

 cumstances which suggest themselves, such as the introduction of 

 water by a hand pump, the removal of an obstacle from the forcing 

 pump which supplies the boiler with water, &c., a less obvious train of 

 circumstances has been assumed as operative. When water is sudden- 

 ly relieved from pressure, this hypothesis asserts that it foams up, and 



* This, with other errors which these Reports would have explained, if 

 circulated in a popular form, appears in the evidence before the coroner's in- 

 quest in the matter of" the late explosion at Hull. 



