OBSERYEIl AND RECORD 



OP AGRICULTURE, SCIENCE, AND ART. 



EDITED BY D. PEIRCE. 



:no. 8 ] 



Philadelphia, Mouday, May 6, 1839. 



[Vol. I. 



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From M. Faraday's Lecture. 

 gurney's oxy-oiL lamp. 

 In the Catopric system practised in 

 our light-houses, a light of seven-eighths 

 of an inch in diameter is placed in the 

 focus of a parabola, which light gives 15 

 degrees of divergence, and consequently 

 each reflector illuminated 15 degrees of 

 the horizon. In the Dioptric system, as 

 practised on the French coasts, a light of 

 three and a half inches in diameter is ne- 

 cessary to give the required divergence. 

 The lime light, though one of great inten- 

 sity, gives no divergence; when placed in 

 a parabola, it throws parallel rays; and 

 when placed in the centre of the Polyzo- 

 nal lens, could not be made to give one 

 degree of divergence. In the spring of 

 1835, Mr. Gurney proposed, by combin- 

 ing oxygen with the flame of wax or oil, 

 to obtain a light of great power to which 

 these objections would not apply. In ex- 

 planation of this light, we must first ob- 

 serve the well known fact, that oxygen 

 increases the brilliancy of burning bodies 

 to a very great extent; thus sulphur, which 

 burns in atmospheric air with a pale blue 

 and scarcely visible flame, when put into 

 oxygen, gives a very intense light, and 

 phosporous, when so surrounded, gives 

 out a light so intense that the eye cannot 

 bear it. The same happens with char- 

 coal, and with the flame of oil or wax, 

 or other bodies which contain it. Dr. 

 Priestly proposed to supply the common 

 argand burner with oxygen instead of 

 common air, and made a long series of 

 Vol. I.— 8. 



experiments with a view of producing a 

 light of this description. All flame is 

 hollow, or, in other words, consists of a 

 thin film or bubble of ignited matter, 

 which surrounds and contains a quantity 

 of the decomposed combustible body sup- 

 plying it. In the flame of spirits of wine, 

 the interior of the film is chiefly filled 

 with hydrogen; in that of oil or wax it is 

 filled with separated carbon — defiant gas. 

 Dr. P. applied oxygen to the outside of 

 the film or bubble, or rather in tJie argand 

 lamp, which he used, double cylindrical 

 films. The outside portion of the flame 

 consists, in its burning state, of half con- 

 sumed carbon in the act of combination 

 with the atmosphere. The oxygen, there- 

 fore, in Dr. P.'s arrangement, met with 

 carbon in a half state of combination, and 

 produced only a brilliancy in proportion. 

 Mr. Gurney proposed to introduce the 

 oxygen into the interior of the bub- 

 ble, and to strike the film, or its out- 

 side surface where the carbon was pure 

 and uncombined. He did so ; and 

 succeeded in the construction of this 

 light for the Catopric system ; there 

 are four small flames in a line of about 

 three-eighths of an inch in diameter each; 

 the oxygen is introduced by a small jet, 

 the light from each jet is equal in quan- 

 tity to two and a half, making in all, ten 

 ordinary argand burners. The diver- 

 gence of it in a parabola is fifteen degrees. 

 The light for the polyzonal lens consists 

 of a circular series of seventeen films or 

 bubbles of flame — and stuck on the inte- 



