272 FISHES. 



The earthy substance is phosphate of lime and magnesia, together 

 with oxide of iron, which is supposed to be combined with phosphoric 

 acid; there is also a slight quantity of sub-carbonate of lime. The 

 animal matter is of two kinds ; one is of the character of nitrogen 

 or azote, and it is the basis of cartilage ; the other, of a fatty nature, 

 is a sort of oil by which it is impregnated. 



The cartilage of the bones of fishes differs much from that of the 

 mammalia and birds, for it yields when boiled in water, no gelatine 

 whatever. 



The oil consists of a large proportion of oleine, to which are added 

 in very minute quantities two principles, one of Avhich is odorous, and 

 the other a yellow colouring matter. The oil is changed into soap 

 with great facility, and when so treated gives off oleic acid, glycerine, 

 and a very minute quantity of margaric acid, so that, if this acid l)e 

 supplied by stearine contained in the oil, the stearine cannot certainly 

 exist in any great quantity in the oil. 



The bones of a carp and a perch having been placed in a vacuum, 

 and dried until they were incapable of yielding no more water, 

 s\istained a loss of their original weight equal to eighty-seven cen- 

 tiemes. In one hundred parts the following components Avere found : 



Cartilaginous azotic matter 36 5 



Oil chiefly consisting of oleine 19 .5 



Phosphate of lime 37 



Sub-carbonate of lime 5 .5 



Phosphate of magnesia and oxide of iron 7 



Sub-carbonate of soda, sulphate of soda, and chlo- 

 ride of soda, (sea salt) ... 8 



Total 100 



In the cartilaginous fishes, or chondropterygians, there is a greater 

 proportion of water. The comparative quantity of soluble salts, that 

 is, of the chloride of soda, sub-carbonate of soda, and especially of the 

 sulphate of soda, is much greater, whilst on the contraiy the propor- 

 tion of the phosphates is considerably less ; but their animal matter is 

 the same in the azotic substance and the oil. The vertebrae of the 

 Pilgrim Squalus maximus, analyzed when it was fresh, yielded in one 

 hundred parts, 



Water 90 



Azotic matter of cartilage and oil 6 48.5 



Sulphate of soda 1 8.59 



Chloride of soda 1 362 



Subcarbonate of soda 2 



Phosphate of lime and magnesia; oxide of iron, 



of alumnina, and silicum 094 



Total 100 



