X.] PANCREATIC DIGESTION. 85 



11. To Peptonise Milk. A pint of milk is diluted with a 

 quarter of a pint of water, and heated to a lukewarm temperature, 

 ahout 140 F. (60 C.). Or the diluted milk may be divided into 

 two equal portions, one of which may be heated to the boiling- 

 point and then added to the cold portion, the mixture will then be 

 of the required temperature. Two tea-spoonfuls of liquor pancrea- 

 ticus, together with about fifteen grains, or half a level tea-spoonful, 

 of bicarbonate of soda, are then mixed therewith. The mixture is 

 next poured into a jug, covered, and placed in a warm situation to 

 keep up the heat. In a few minutes a considerable change will 

 have taken place in the milk, but in most cases it is best to allow 

 the digestive process to go on for ten or twenty minutes. The 

 gradually increasing bitterness of the digested milk is unobjection- 

 able to many palates ; a few trials will, however, indicate the limit 

 most acceptable to the individual patient ; as soon as this point is 

 reached, the milk should be either used or boiled to prevent further 

 change. From ten minutes to half an hour is the time generally 

 found sufficient. It can then be used like ordinary milk. 



ADDITIONAL EXERCISES. 



12. Preparation of Indol. Place i kilogram of fresh fibrin in a 6 -litre jar 

 with 4 litres of water (to which i gram KH 2 P0 4 and .5 gram MgS0 4 are 

 added). Mix this with 200 cc. cold saturated solution of sodic carbonate, and 

 add to the whole a quantity of putrefying flesh-juice and some pieces of the 

 putrid flesh as well. Cork the vessel, a vent-tube being placed in the cork, 

 and place it aside f^r 5-6 days at a temperature of 40-42 C. Distil and 

 acidify the strongly ammoniacal distillate with HC1, add some copper 

 sulphate, and filter. Shake up equal volumes of the distillate and ether in a 

 separation funnel. Allow the filtrate to settle, run it off, add some fresh 

 filtrate, and shake again with the same ether. Distil the ethereal extract to 

 about one-fourth of its volume, shake up the residue very thoroughly with 

 caustic soda (to remove phenol and traces of acids). Distil the ether, and 

 after the addition of caustic soda distil the oily indol. The distillate is shaken 

 up with ether, and the ethereal extract is evaporated at a low temperature, 

 when crystals or plates of indol separate. This preparation usually contains 

 some skatol. (Drechsel after Salkowski.} 



SOME NITROGENOUS DERIVATIVES OF THE FOREGOING. 



13. Leucin or a-Amido-isobutylacetic acid, C 6 H ]3 N0 2 = 2(CH 3 )CH CH 2 

 CH(NH. 2 )CO.OH, and Tyrosin or Paraoxyphenyl-a-Amidopropionic acid, 



C,,H n N0 3 =C c H 4 <Q^(NH 2 )CO. OH. These two bodies are obtained 



together from nearly all proteids when the latter are decomposed by the action 

 of acids. The former belongs to the fatty bodies, and tyrosin to the aromatic 

 group, and is a derivative of benzene (C e H 6 ). 



