CHAP. III.] ANTI-PEPTONE. 227 



The following actual examples taken from Kiihne and Chitten- 

 den's researches will explain the processes to be followed in pre- 

 paring anti-peptone. 



300 grins, of dry fibrin, which had been purified as stated above 

 and as a last process had been boiled in water and the water 

 expressed with the hand, were found to 'weigh 970 grms. This 

 quantity of inoist fibrin was placed in three litres of a 0'25 per cent, 

 solution of sodium hydrate, to which J per cent, of thymol had been 

 added. The infusion obtained (as explained previously, viz. by the 

 salicylic acid and NaHO and thymol method) from 88 grms. of 

 pancreas was then added to the fibrin and the whole mixture 

 digested at 40C. during six days. The very first day nearly the 

 whole of the fibrin was dissolved, though a little yet remained 

 undissolved and floated on the surface of the liquid. 



The digested liquid was slightly acidulated with acetic acid, 

 )iled, and filtered through cloth, and the filtrate concentrated to 

 litre. On cooling, there crystallised out the greater part of the 

 iucine and tyrosine which had been formed, and to the brownish 

 r rup which was drained off alcohol was added until a precipitation 

 )f peptones commenced. The liquid was then boiled, to dissolve any 

 >recipitated peptone, and set aside again to crystallise. The filtrate 

 >m the second crystallisation, now tolerably free from amido-acids, 

 ras saturated with ammonium sulphate. This reagent besides pre- 

 dpitating any albumoses which may be present, carries down, 

 wording to Kiihne and Chittenden, many accidental impurities, 

 ind seems to precipitate very perfectly the trypsin which may 

 , 7 et be present in the liquid. The filtrate from the ammonium 

 sulphate precipitate was then freed from a great part of the salt by 

 concentrating it, cooling and allowing the salt to crystallise out, the 

 separation being aided by the addition of considerable quantities of 

 alcohol. In order finally to free the peptone from the ammoniacal 

 salt, the same process was followed as for the preparation of ampho- 

 peptones from fibrin (see page 137) ; i.e. the solution was boiled with 

 barium hydrate and barium carbonate, and after expulsion of the 

 whole of the ammonia by boiling, the compound of anti-peptone 

 and barium was decomposed by means of sulphuric acid. The 

 peptone was repeatedly precipitated with alcohol. 'When dried at 

 105 the anti-peptone obtained from 300 grms. of fibrin weighed 

 120 grammes. 



Kiihne and Chittenden found as much difficulty in drying anti- 

 peptone as they had encountered in the case of ampho-peptones. 



Reactions of Anti-peptone, like ampho-peptone, is only corn- 

 solutions of pletely precipitated from its solutions by the following 

 anti-peptone reagents: tannin, a solution of iodide of mercury in 

 'romaibu- potassium iodide; and almost completely precipitated 

 by phospho-tungstic acid, phospho-molybdic acid and 

 picric acid. 



152 



