Mr Gordon on the Decomposition of Oil Gas. 325 



Gmelin,) and A. antarcticus, Garn. The former runs so 

 fast that it is easier to procure a specimen which is flying. 



Of the genus Anas four species are recorded ; Anas cinerea, 

 Gmel. (J. brachyptera, Lath.) has short wings, and it is easy 

 by firing upon a group of them to drive them upon the land, 

 when they become an easy prey, from not being able to fly. 

 The sailors thus killed numbers of them with sticks. It is 

 this species which was called race-horses by the sailors in the 

 voyages of Wallis and Cook. The second species is the " Mi- 

 louin des Malouines jT the third the i( Canard a bee jaune et 

 noir d'Azara f? and the fourth the Anas superciliosa of La- 

 tham. The flesh of the last is said to be delicious. 



Art. XXXVI. — On a Remarkable Decomposition of' Carbu- 

 retted Hydrogen by its Rapid Escape from a Portable Gas 

 Lamp. By David Gordon, Esq. Engineer to the Lon- 

 don Portable Gas Light Company. In a Letter to the 

 Editor. 



My Dear Sir, 

 I think it may be interesting to you to be informed of an ac- 

 cidental discovery which my son Alexander and I made when 

 starting the portable gas works at Manchester. 



You are aware that the portable gas lamps are usually fill- 

 ed with compressed gas to the extent of thirty atmospheres. 

 When proceeding to do so the first time at Manchester, the 

 safety valve of the compressing machinery happened to blow 

 at about twenty-seven atmospheres. Most of the attendants 

 were unacquainted with the operation, and as the valve made 

 to them> an alarming noise, it was some little time before the 

 steam-engine, which works the condensing pumps, could be 

 stopped. When we went to examine the safety valve, we 

 were surprised to observe that all the metallic part of the valve, 

 upon which the gas had rushed, was covered with a black 

 moist carbonaceous substance, and the contiguous brick wall 

 with dry black carbon, the moisture in this latter case having 

 been absorbed by the brick. 



Since that time, my son has repeatedly exhibited the dis 



