30 PHYSIOLOGICAL CHEMISTRY. 



washed with a saturated salt solution, and then treated with a 10 

 per cent NaCl solution; what remains is called dysalbumose. The 

 filtered solution is repeatedly and completely dialyzed. A part 

 separates which is heteroalbumin, while the protalbumose remains 

 dissolved in the liquid. The above-mentioned filtrate which has 

 had the primary albumoses removed and saturated with common 

 salt is treated with acetic acid which has previously been saturated 

 with salt. The precipitate consists of deuteroalbumose. The re- 

 sulting filtrate, from which a new precipitate separates on satura- 

 tion with ammonium sulphate, contains the remainder of the 

 deuteroalbumose and a little peptone. 



For the preparation of true peptone we may use a prolonged 

 pepsin digestion, but much quicker results are obtained by the 

 use of the trypsin digestion. The neutralized liquid is heated 

 to boiling, filtered, sufficiently concentrated, and saturated while 

 boiling hot with ammonium sulphate. The albumoses which sepa- 

 rate are filtered. If any peptone is present in the cold filtrate, a 

 beautiful biuret reaction is obtained by the addition of very strong 

 caustic soda solution and a little' copper sulphate solution, though 

 when the products of pepsin digestion are employed this may 

 depend on non-precipitated deuteroalbumose. The greater part of 

 the ammonium sulphate may be removed from the filtrate by evap- 

 oration and crystallization or by partial precipitation by alcohol. 

 What now remains is separated by the addition of barium hydrate, 

 and lastly by barium carbonate with heat. The filtrate is concen- 

 trated and precipitated by alcohol. In regard to the more detailed 

 accounts of the proposed methods for the preparation of pure pep- 

 tone and the different albumoses the reader is referred to the works 

 of KUHNE, CHTTTENDEN, and NEUMEISTEK. 



The methods for the detection of albumoses and peptones in 

 fluids and tissue are not very accurate, and therefore, as they can- 

 not be given without criticism which does not enter into the scope 

 and plan of this work, they will be omitted. 



Coagulated Albuminous Bodies. Albumin may be converted into 

 the coagulated condition by different means : by heating (see page 

 18), by the action of alcohol, especially in the presence of neutral 

 salts, and in certain cases, as in the conversion of fibrinogen into 

 fibrin (Chapter IV), by the action of an enzyme. The nature of the 

 processes which take place during coagulation is unknown. The 

 coagulated albuminous bodies are insoluble in water, in neutral 

 salt solutions, and in dilute acids or alkalies, at normal temperature, 

 They are dissolved and converted into albuminates by the action of 

 less dilute acids or alkalies, especially on heating. 



