CHAP. II.] ARTIFICIAL GASTRIC JUICE. 83 



3. Of all methods yet suggested for the preparation of an active 

 artificial gastric juice, the following, suggested by Klihne and Chitten- 

 den, furnishes the most active preparation, and also one in which 

 the proportion of extraneous products is in smallest amount. The 

 mucous membrane, from the cardiac region of several pigs' stomachs, 

 say five or six, is reduced to a fine state of division and is then 

 digested for fourteen days at 40 C. with from two to three litres of 

 - 5 per cent, hydrochloric acid. 



At the end of this time in presence of so large a quantity of 

 pepsin and acid, all but traces of the so-called albumoses have been 

 converted into peptones, which are in solution together with pepsin, 

 although there remain undissolved a small proportion of foreign 

 matters, nucleins, anti-albumid, &c. 



The liquid is filtered and saturated with powdered ammonium 

 sulphate. This salt in addition to its power of precipitating any 

 albumoses which may be present, throws down the whole of the 

 pepsin. The precipitate is collected on a filter, washed with 

 saturated solution of ammonium sulphate, and is then dissolved in 

 0*2 per cent, hydrochloric acid. 



To the acid solution is added O25 per cent, of thymol, and it is 

 then dialysed in running water, until the whole of the ammonium 

 sulphate has been removed. 



On opening the dialysing tubes a precipitate is found, which is 

 soluble in 0'2 per cent. HC1, and furnishes a very active gastric 

 juice. The filtrate also when acidulated so as to contain 0*2 per 

 cent, of HC1, furnishes an intensely active gastric juice 1 . 



4. Take a glycerin extract of mucous membrane of the stomach 

 and mix with dilute hydrochloric acid containing 0'2 per cent. HC1. 



5. A solution of pepsin prepared by methods afterwards to be 

 described, may be added to dilute hydrochloric acid of suitable 

 strength, so as to furnish an artificial gastric juice of great purity. 



strength of We have recommended above that dilute hydro- 



hydrocnioric chloric acid containing O'l or 0'2 per cent, of HC1 



acid for ar- should be used, for it resulted from the observations of 



Brticke that, cceteris paribus, pepsin acts most ener- 



getically on many proteids if present in a fluid con- 



taining approximately this quantity of hydrochloric acid ; the most 



favourable strength for the solution of fibrin being 0'086 0*088 per 



cent, whilst for coagulated white of egg it is as high as O'l 2 or 016 



per cent. It would appear however from the observations of Kuhne 



and Chittenden that the digestive process is, in some cases at least, 



1 Kiihne and Chittenden, 'Ueber die Peptone.' Zeitschrift fur Biologie, Vol. xxn. 

 p. 423. And in Studies from the Laboratory of Physiological Chemistry of Yale Uni- 

 versity, edited by B. H. Chittendeu, Ph.D., Vol. n. (1887) p. 18 and Chittenden and 

 Bolton, 'Egg-Albumin and Albumoses.' Stud, from Lab. of Phys. Chem. of Yale 

 Univ. Vol. ii. p. 135. 



UNIVERSITY) 



