Shining Fish, Flesh, and Wood 491 



whereas phosphorus is not. (2) Wood is luminous in many more 

 non-respirable gases than phosphorus. (3) Wood luminescence dis- 

 appears but phosphorus takes fire in muriatic acid gas. (4) Wood 

 emits less, and phosphorus more light in rarefied air. (5) Wood 

 luminesces in vacuo but phosphorus does not. (6) Wood lumines- 

 cence disappears when heated in oxygen while phosphorus burns. 

 (7) Wood produces CO2 while phosphorus does not. (8) Moisture 

 and wet promote the luminescence of wood but are impediments 

 to the luminescence of phosphorus, which will not light under water. 



Some of the above statements are incorrect, that wood luminesces 

 in vacuo; other differences are connected with the peculiar behavior 

 of phosphorus luminescence at different oxygen tensions (see Chap- 

 ter XIII) . However, many of the differences are quite striking and 

 Boeckmann concluded: *^ 



" Phosphorescent wood, therefore differs essentially from artificial 

 phosphorus by the conditions requisite for its being luminous; and 

 therefore the assertion of Spallanzani, that the greatest analogy 

 exists between the luminous phenomena of these two substances 

 must lose some of its weight." He held that " The extinction of 

 the light of rotten wood in different mediums does not so imme- 

 diately arise from want of oxygen gas as from some change which 

 the wood itself has experienced." 



NATHANIEL HULME 



England's contribution to the study of gases on luminous fish and 

 wood was made by Nathaniel Hulme, a practising physician in 

 London. His two important papers on " Light which is Spon- 

 taneously Emitted, with some Degree of Permanency, from Various 

 Bodies," were published in 1800 and 1801. The 1800 paper, deal- 

 ing with light from a concoction of fish in sea water, is divided into 

 a number of sections with such headings as: 



I. The Quantity of Light emitted by putrescent Animal Substances is 

 not in proportion to the Degree of Putrefaction in such Substances, as 

 is commonly supposed; but on the contrary, the greater the Putrescence, 

 the less is the Quantity of Light emitted. II. The Light here treated of 

 is a constituent principle of some Bodies, particularly of Marine Fishes, 

 and may be separated from them, by a peculiar process; may be retained, 

 and rendered permanent for some time. It seems to be incorporated 

 with their whole substance, and to make a part thereof, in the same 

 manner as any other constituent Principle. 



After pointing out that some substances preserve and others extin- 

 guish spontaneous light, Huhne said that when extinguished "it is 



