THE 



PHILOSOPHICAL MAGAZmE. 



I. Description of anew Eudiometer, invented by H.Davy, 

 Esq., S. R. S., for the ComlustiGn of Oxygen and Hy- 

 drogen Gases. By R. Knight, Esq. 



To Mr. Tilloch. 



1 HE enclosed drawing (Plate I.) represents a eudiometer 

 we lately made on the suggestion of Mr. Davy, for the 

 more commodious display or ihe formation of water, by the 

 combustion of the two gases, oxygen and hydrogen, by 

 means of the electric spark. 



The instrument consists of a strong cylindricahaiass tube 

 A, to rccefve the gases ; open at the lower end, of^the capa- 

 city of two cubic inches, and graduated into decimal parts ; 

 and a stand to which the tube is attached, by a clasp B, and 

 screw S. The stand is composed of the clasp and screw B, S, 

 and an iron cylinder C, containing a strong spiral spring, on 

 the principle of the pocket steelyard, the spindle or central 

 bar of which is fixed on the thre.' k-et D, in order that it 

 may be secured firmly on the side uf a mercurial bath, with 

 the mouth of the tube immerged in the quicksilver. 



By this arrangement, the sudden and violent expansion 

 which takes place at the moment of the combustion of the 

 gases is relieved by the elasticity of the spring, which, by 

 yielding, allows the glass tube to be heaved up a little way, 

 without being driven from its situation. The success of the 

 experiment is thus secured, and all danger of accident to. 

 the apparatus is effectuallv prevented. 

 Vol. 31. No. 121. June 1808, A 2 H. Life 



