492 KTTHNE'S NEW METHOD OF PURIFYING PEPTONES. [BOOK n. 



jected to renewed digestion for a period of many weeks (six or eight) 

 with a highly acid solution of pepsin. The acid pepsin solution 

 employed should, in the first instance, contain 0'5 per cent, of HC1, 

 and, after the albumoses have been introduced and digestion has 

 commenced, hydrochloric acid must be added, in the proportion 

 of at least 3 4 per cent, of the weight of the albumoses subjected 

 to digestion. Ktihne states that if these conditions be fulfilled 

 the albumoses digested may amount to 4 or 5 per cent, of the 

 acid pepsin mixture. The Author having three times repeated 

 Kiihne's method, on a large scale, with digestive mixtures containing 

 varying quantities of albumoses, is inclined to think that a greater 

 proportionate yield of amphopeptone is obtained when the percent- 

 age of albumoses is low than when it is high. It must be stated, 

 however, that the difficulties, the labour, and the expense of the 

 operations increase enormously with the increase of dilution. 



To prepare the pepsin solution which should be employed in 

 making large quantities of amphopeptone, the following process 

 should be employed (which is the same as that described at page 83, 

 the final dialysis being omitted) : the mucous membrane of the 

 cardiac case of the stomach of two or three pigs, having been washed 

 and minced, is digested for at least a week with dilute hydrochloric 

 acid (containing 0'5 per cent. HC1). The dark-coloured artificial 

 gastric juice thus obtained is, after filtration, saturated with ammo- 

 nium sulphate, which precipitates the albumoses ; these carry down 

 with them the whole of the pepsin. The precipitate is washed with 

 a saturated solution of ammonium sulphate ; the latter is separated 

 as completely as possible from the precipitate, which is ultimately 

 pressed between filter paper. The pepsin-containing albumoses are 

 found to be entirely soluble in 01 0*5 solution of HC1, furnishing a 

 clear and colourless solution, which possesses intense peptic activity. 



The successive processes of precipitation with ammonium sulphate 

 which have been referred to as necessary to the complete separation 

 of albumoses and which have all to be carried out at the boiling 

 temperature, necessitate very large quantities of ammonium sul- 

 phate, so that in order to obtain one hundred grammes of ampho- 

 peptones free from albumoses the experimenter will employ, in the 

 successive operations, many kilogrammes of the ammonium salt. 

 The albumoses which separate when ammonium sulphate is added, 

 to complete saturation, to the mixture of albumoses and peptones 

 which has been rendered alkaline by ammonium carbonate and 

 ammonia, at first partially separate in a flocculent form, but in great 

 part as a dark brown melted scum, which is best removed by a 

 perforated ladle ; the brown colour is obviously the result of processes 

 of oxidation brought about by the atmospheric oxygen in the 

 presence of free ammonia. This dark scum rises to the surface again 

 and again and must be removed. 



albumose and proto-albumose (the former preponderating very largely) with only a 

 trace of hetero-albumose and no dys-albumose. 



