SILK. 345 



bonate of ammonia and an empyreumatic oil. A portion of it 

 put into concentrated sulphuric acid remained twenty-four hours 

 unaltered. When heated it became black, and sulphurous acid 

 was given out. It does not dissolve in dilute sulphuric acid even 

 though assisted by heat. Nor does nitric acid attack it at the 

 common temperature of the atmosphere. But when the albumen 

 is moist, concentrated nitric acid dissolves it and converts it into 

 oxalic acid. 



Muriatic acid does not attack it at the common temperature of 

 the atmosphere, but dissolves it when assisted by heat ; or when 

 the albumen is moist. Both common and pyrophosphoric acid 

 blacken and decompose it. When dissolved in concentrated ace- 

 tic acid the albumen gives a solution having an oily appearance, 

 which Mulder considers as a very remarkable property. Prus- 

 siate of potash throws down a beautiful green precipitate not 

 soluble in water. 



It is soluble in potash, soda, and ammonia, and is again pre- 

 cipitated by acids. It is insoluble in the alkaline carbonates. 



Mulder subjected it to analysis and obtained, 

 Carbon, . 54-005 

 Hydrogen, . 7-270 



Azote, . 15.456 



Oxygen, . 23-269 



100-000* 



These numbers approach those obtained by Mulder from the 

 albumen of eggs and of blood. 



4. The cerin was grey, specifically lighter than water, melted 

 when gently heated, and burnt with a very light flame. It was 

 insoluble in water, but dissolved readily in alcohol, ether, fixed 

 and volatile oils. 



Concentrated sulphuric acid decomposes it at a high tempe- 

 rature. Nitric acid and muriatic acid do not attack it. When 

 boiled with caustic potash it is partly dissolved ; but again se- 

 parates when the solution cools. When alcohol is added it does 

 not dissolve the matter unless heat be applied. Ether does not 

 dissolve it. It is soluble in caustic ammonia and in concentrat- 

 ed acetic acid. 



5. The colouring matter extracted from yellow silk was of a 



* Poggendorf s Annalen, xl. 270. 



