181 4. J Chemical Analysis of Caviar. 101 



horny-looking substance, equally insoluble in water and alcohol. 

 Pure caustic potash ley dissolved it, and it was thrown down again 

 by the addition of an acid. This substance, which possesses the 

 properties of albumen, when fully dried, weighed 26 grains. 



The watery solution thus freed from albumen, being properly 

 concentrated, deposited 26 grains of common salt in small cubes, 

 mixed with a little alkaline sulphate. The mother ley contained a 

 portion of slime scarce capable of being weighed. It was 

 mixed with common salt, but easily separated by washing it with 



water. 



I now allowed the portion of cariar which was insoluble in water 

 to dry, by exposing it to a very gentle heat. In this state it still 

 retained very strongly its peculiar taste. It was repeatedlv digested 

 in alcohol, the solution was mixed with water, heated, and allowed 

 to cool again. By this means 18 grains of an unctuous yellow 

 coloured oil were obtained. The residue left by the alcohol undis- 

 solved had lost the peculiar taste of caviar. The liquid freed 

 from the oil was found to contain nothing but an atom of common 

 salt. 



What the alcohol had left undissolved was boiled for an hour in 

 pure water. The filtered water, being evaporated to dryness, left 

 only an atom of jelly. The portion undissolved in water weighed, 

 after being dried, 104 grains. It had the colour of caviar, and was 

 indurated albumen. When burnt it emitted a very fetid animal 

 smoke. The coal which remained behind was bumt'to ashes. The 

 ashes weighed H grain. They contained no alkali; but consisted 

 of common salt, sulphate of potash, phosphate of lime, and a 

 trace of iron. 



The constituents furnished by the preceding analysis of 420 

 grains of caviar are the following : — 



Grains. 



Pure dry albumen from the solution of caviar 26 



Unctuous oil jg 



Insoluble or indurated albumen 102 



Common salt with some alkaline sulphate "K 



jelly ; V 



Phosphate of lime t 2 



Oxide of iron V 



Water as the deficiency 044 



420 



From the preceding analysis it follows that caviar contains a 

 notable portion of soluble albumen, which constitutes so nourishing 

 an article of food, that the peculiar taste of caviar is to be ascribed 

 to .111 oil, which is the same as that contained in all the ova of 

 animals so far as I have hitherto examined them, namely, in those 

 ol insects (butterflies and grasshoppers), of amphibia, and of birds 



