126 OXIDES WITHOUT AZOTE NOT OILY. 



namely, ammonia, murexane, alloxane, alloxantin, and urea. 

 Wohler and Liebig consider it as a combination of various 

 amides. Yet the decomposition of thionurate of ammonia when 

 decomposed by the acids gives a greater number of products 

 than even murexide. 



CHAPTER II. 



OXIDES NOT CONTAINING AZOTE, AND NOT OILY. 



THESE bodies have been hitherto very imperfectly investigated. 

 We can enumerate in the present state of our knowledge only 

 four such substances, namely, 



1. Melain. 3. Diabetes sugar. 



2. Oonin. 4. . Sugar of milk. 



These bodies will constitute the subject of the following sections : 



SECTION I. OF MELAIN.* 



This name has been given by Bizio to the black matter which 

 constitutes the essential constituent of the ink of the cuttle-fish. 

 Jt was first examined by Mr G. Kempf in the year 1813, after- 

 wards by Dr Prout in 1815 ;J and finally by Bizio. 



The black liquor of the cuttle-fish is secreted in a bag or blad- 

 der situated near the ca3cum, which communicates by a narrow 

 duct, with an opening in the upper part of the belly of the fish. 

 When chased by other fishes, the cuttle-fish is said to discharge 

 a quantity of this liquid, which, by rendering the water muddy, 

 enables it to escape from its enemies. Dr Prout found that when 

 the black matter in this ink is mixed with water, it takes at least 

 a whole week to subside. It is therefore admirably adapted for 

 the purposes of concealment. 



The ink of the sepia when fresh is a black glairy liquid, of a 

 viscid consistence, a peculiar fishy smell, and very little taste. 

 When allowed to dry in its bladder, it becomes hard and brittle, 

 has an imperfectly conchoidal fracture, a brownish-black colour, 

 and exhibits a slight peacock-tail lustre on exposure to a strong 



* From fixate, black. f Nicholson's Jour, xxxiv, 34. 



| Annals of Philosophy, v. 417. Brugn. Jour, xviii. 18. 



