75 



^Potassium burned in water.) This experiment reminds the lec- 

 turer of some juvenile experiences of a chemical student, who shall 

 be nameless before this audience; That young gentleman, in the 

 ardour of his youth, was in the habit of indulging in chemical 

 investigations in the drawing room to the deterioration of furniture 

 and the general discomforts of the household. After repeated 

 warnings that this was not to be tolerated, the parental authorities 

 resolved on confiscating, accordingly, the limited stock of chemicals 

 in the possession of the said young gentleman, and all, as is the 

 rule in these cases of the most dangerous character, were seized. 

 Among them was a bottle containing phosphorus ; this happened 

 to be the first, and was thrown in the fire. The result was a con- 

 flagration almost worthy of the pyrotechnist of the Crystal Palace. 

 To make assurance doubly sure, the remainder were taken to the 

 Iback yard, and the process of throwing down the drain was com- 

 menced. The lot to be selected for this fate, however, was a 

 bottle containing this same substance — potassium — which has been 

 brought before your notice to-night. The result of this expedient 

 meeds no comment. 



This is a property not only possessed by potassium, other 



metals also act similarly; so also does a substance knoAvn as calcic 



phosphide. This has met with a useful application in signalling 



at sea, as this substance is the body used in the manufacture of 



Holme's signal lights. In these cases it is not the water which 



burns, but a chemical action takes place which liberates a 



i combustible body, and the heat produced suffices to cause ignition. 



We find, on the other hand, that certain substances are protected 



from combustion while under water, but on rising to the air ignite 



I spontaneously. As an instance, phosphoretted hydrogen may be 



J mentioned. The flash of light resulting from each bubble, and 



I the beautiful wreaths of smoke, are especially noticeable. Plame 



[is not dependent for its existence on atmospheric air, or its active 



constituent oxygen ; combustion takes place in other gases, among 



them chlorine. 



