THE BUDE LIGHT. 143 



many other contrivances which act on the same principle, 

 consists obviously in increasing the supply of oxygen by 

 facilitating the access of common air to the combustible 

 substances in the flame. But common air contains but a 

 small portion of oxygen one fifth only of its volume ; the 

 remainder consists of other gases, which not only render 

 no aid to the combustion, but positively impede it by oc- 

 cupying the space and keeping back the oxygen from ap- 

 proach. The remedy for this difficulty would obviously 

 be supplying the flame with pure oxygen instead of a mix- 

 ture containing four fifths of useless matter. This is done 

 in an arrangement which has been quite celebrated, and 

 which is known as the Bude Light. This light will, how^ 

 ever, be more particularly referred to in the next chapter. 



