10 ORGANIC CONSTITUENTS. 



tlieor}^, a simpler method of obtaining this compound. When 

 fibrin or albumen of inflamed or healthy bloody of serum of the 

 blood, or of hen's eggs, is boiled with water, after four hours' 

 boiling, principles are always obtained which are soluble in water, 

 whilst the greater part remains undissolved. On repeating the 

 ebullition every four hours with fresh water, fresh quantities of 

 soluble matter are extracted, the insoluble portion becoming 

 poorer in carbon, hydrogen, and nitrogen, but richer in oxygen, 

 until the composition is finally constant. Moreover, the portion 

 of albumen or fibrin soluble in Avater when evaporated, extracted 

 with alcohol, and treated with cold w^ater, is almost entirely so- 

 luble in it, and likewise contains less carbon, hydrogen, and 

 nitrogen, but more oxygen than protein. The substances taken 

 up by the alcohol are merely products of decomposition of the 

 soluble portion of the fibrin or albvimen. It is, moreover, the 

 decomposition of this portion that gives rise to the ammonia 

 that is produced on distilling albumen or fibrin with water. 



The soluble matter taken up from the fibrin or albumen by 

 prolonged ebullition is in every respect identical with the trit- 

 oxide of protein Avhich Ave have already described ; it exists 

 moreover ready-formed in the buffy coat of the blood. From 

 whichever of these sources we procure it, whether from chloro- 

 proteic acid, from albumen or fibrin, by prolonged ebullition, 

 or from the buffy coat of the blood after a comparatively short 

 ebullition, it possesses the same properties. It is soluble in cold 

 water, but not in ether, alcohol, essential or fat oils ; it has nei- 

 ther an acid nor alkaline reaction. It is always precipitated in 

 the same manner from its aqueous solution by diluted nitric, 

 sulphuric, hydrochloric, neutral and basic phosphoric, and tannic 

 acids; by solutions of chlorine, bichloride of mercury, neutral and 

 basic acetate of lead, nitrate of silver, sulphate of zinc, and 

 peroxide of iron. It forms with metallic oxides a class 

 of double salts, which are composed according to the formula 

 (C,o H3. N, 0,,4-M0) + (C,, H,. N, 0., + H0_). 



Tritoxide of protein is not precipitated by dilute acetic acid, 

 neutral salts of potash and soda, chloride of barium, hydrochlo- 

 rate of ammonia, nor by that very delicate test for protein, fer- 

 rocyanide of potassium. It dissolves gradually in solutions of 

 potash, soda, and ammonia. When thoroughly dried, it occurs 

 as an amber-coloured powder. Nitric acid converts it into 



