] 815.] On the colouring Matter ejected ly the Cuttle Fish. 4 19 



D. The black residuum was now carefully dried and weighed, 

 in order to constitute a check to the above. Its weight was 195 

 grains" = 7^ P'^'" cent., indicating a loss of l-(>0 in the abcs'e- 

 nientioncd processes. This I considered as tlie pure colouring 

 principle. It was of a fine full black colour, and possessed the 

 shining appearance of powdered charcoal. It was insoluble in tlie 

 muriatic and sulphuric acids, even when assisted by heat. Also in 

 the acetic. Concentrated nitric acid acted on it readily, and wiih 

 considerable energy, abundance of red fumes being emitted; and 

 at length a partial solution, being formed of a very deep reddish 

 brown colour. A solution of pure potash added to this solution 

 produced no precij/itate : but a solution of the subcarbonate of 

 potash produced a slight one. A solution o{ caustic potash, assisted 

 by heat, likewise effected a partial solution of this substance. Also 

 caustic ammonia in a slighter degree. The colour of these solu- 

 tions was of a deeper brown than that in nitric acid. The muriatic 

 and sulphuric acids produced a slight precipitate when added to 

 this alkaline solution, but not the nitric acid. 



It burnt, without melting, with considerable difficulty, emitting 

 the usual smell of burning animal matters, somewhat modified by 

 a fishy odour. It left a very minute portion of reddish ashes, 

 which proved to be a mixture of red oxide of iron, lime, and 

 magnesia, the quantities in the order mentioned, that of the oxide 

 of iron being greatest. Hence 100 parts of this substance contained 



Peculiar black colouring matter 7^*00 



Carbonate of lime 1 0'-iO 



Carbonate of magnesia 7'00 



Muriate of soda ? ~> 



Sulphate of soda ? / ^'IG 



Animal matter analogous to mucus 84 



Loss 1-60 



100-00 



The carbonates of magnesia and lime, from their being so 

 readily extracted almost entirely by the muriatic acid, appear to 

 have been in a state of mechanical mixture only in this substance. 

 The iron undoubtedly formed a component part of it, as it does in 

 the colouring matter of the blood. The quantity I possessed was 

 too small to enable me to make the investigation so complete as 

 could be wished; though, from what has been said, it will appear 

 to lie chiefly characterized by its negative properties. 



Mr. G. Kemp* has made some experiments on this substance in 

 its recent state. He appears to have considered it as consistuig (k\ 

 or at least containing, alliumcn ; but apparently without any very 

 good rcas(Mi. it aj)pcars to me, that all the cH'ects of coagulation, 

 precipitation by alcohol, mineral acids, metalline solutions, &c., 



* Nict), Juuriial, vol. xxxiv. p, 34. 

 2 D'2 



