APP.] CHEMICAL BASIS OF THE ANIMAL BODY. 707 



albumin. One of the most productive methods of obtaining alkali- 

 albumin is that introduced by Lieberkiihn 1 , and consists in adding a 

 strong solution of caustic potash to purified white of egg until the 

 above-mentioned jelly is obtained. This is then cut into small pieces, 

 and dialysed until quite white. The lumps are then dissolved by 

 heating on the water-bath, and the alkali-albumin precipitated by the 

 careful addition of acetic acid. 



Both alkali- and acid-albumin are with difficulty precipitated by 

 alcohol from their alkaline or acid solutions. The neutralisation pre- 

 cipitate however becomes coagulated under the prolonged action of 

 alcohol. 



The body 'protein,' described by Mulder appears, if it exists at all, to be closely 

 connected with this body. All subsequent observers have however failed to confirm 

 his views. 



The rotatory power of alkali-albumin varies according to its source ; 

 thus when prepared by strong caustic potash from serum-albumin, the 

 rotation rises from - 56 (that of serum albumin) to 86, for yellow 

 light. Similarly prepared from egg-albumin, it rises from 38-5 to 

 47, and if from coagulated white of egg, it rises to 58'8. Hence 

 the existence of various forms of alkali-albumin is probable. 



In addition to the methods given above, alkali-albumin may be also readily ob- 

 tained by shaking milk with strong caustic soda solution and aether, removing the 

 aetherial solution, precipitating the remaining fluid with acetic acid and washing the 

 precipitate with water, cold alcohol and aether. 



The most satisfactory method of regarding acid- and alkali-albumin 

 is to consider them as respectively acid and alkali compounds of the 

 neutralisation precipitate. We have reason to think that when the 

 precipitate is dissolved in either an acid or an alkali, it does enter into 

 combination with them. The neutralisation precipitate is in itself 

 neither acid- nor alkali-albumin, but may become either, upon solution 

 in the respective reagent. 



It is probable that several derived albumins exist 2 , differing according to the 

 proteid from which they are formed or possibly according to the mode of their pre- 

 paration, and that each of these may exist in its correlative forms of acid- and alkali- 

 albumin; but the whole subject requires further investigation. 



Acid-albumin, prepared by the direct action of dilute acids on native 

 albumins or on muscle-substance, contains sulphur, as shewn by the 

 brown colouration which appears when the precipitate is heated with 

 caustic potash in the presence of basic lead acetate. Alkali albumin, 

 at all events as prepared by the action of strong caustic potash or soda, 



1 Poggendorff's Annalen, Bd LXXXVI. S. 118. 



2 Morner. Pfluger's Arch. Bd, xvii. (1878), S. 468. 



452 



