136 POPULAR LECTURES AND ADDRESSES. 



strongly to the life-buoy so that neither can be 

 thrown into the water without the other. I must 

 not forget to pluck away these soft solder stoppers 

 from the conical end below, and the top of the 

 projecting tube above. Having done so, I now 

 throw both the life-buoy and rescue light over- 

 board. All this is done within ten seconds of 

 time, after I hear the alarm " a man overboard." 

 You see now the moment the metal vessel plunges 

 into the water, it begins to smoke vehemently, and 

 almost instantly flames rise (Fig. 17). The man in 

 the water sees the light, swims towards it, catches 

 the life-bouy, and supports himself securely by 

 it. No danger now of him sinking or being 



' * heated to a certain degree over cherry red. The phosphorus, by 

 ' ' the heat, is converted into vapour, and the red-hot chalk takes up 

 " this vapour to saturation." "When cooled, the contents, phos- 

 " phuret of calcium and phosphate of calcium " (the former the 

 active ingredient), "are placed in the tin cases and soldered down. 

 "Upon using the signal, the water is admitted, and " acting on the 

 phosphuret of calcium, produces " phosphuretted hydrogen, which 

 " issuing out of the upper orifice, catches fire spontaneously, and 

 bursts into flame." 



1 " The process of manufacture shows that the rescue signals 

 " are free from danger, are not affected by either heat, friction, or 

 " percussion, water alone can ignite them." 



