CHAP. II.] LABORATORY WORK ON GASTRIC DIGESTION. 181 



In calculating the results, all the ammonia found is calculated 

 as existing in combination with .chlorine. The amount of chlorine 

 which was required to combine with ammonia and with the other 

 bases (See c.), reckoned as sodium, is then found, and is deducted 

 from the total amount of chlorine found by operation b. The differ- 

 ence represents the chlorine existing as free HC1, of which the 

 amount is then calculated. 



The process above described is one which should not be under- 

 taken by any one who is not thoroughly familiar with the methods 

 of inorganic analysis. This remark applies still more forcibly to 

 the original process of Carl Schmidt, for which the reader is referred 

 to the original memoir 1 . 



7. Determination of the proportion of acids soluble in water and ether. 



It has been stated (p. 96) that valuable information as to 

 le nature of the acid of the gastric juice has been obtained by 

 I/ichet by employing Berthelot's method of determining the so-called 

 efficient de partage. 



For carrying out this method there are required, 



(1) An accurately graduated burette. 



(2) A pipette which delivers say 25 c.c. 



(3) Two pipettes which deliver 10 c.c. To the upper end of 

 me at least of these pipettes is attached an india-rubber tube with a 

 )inch-cock. 



(4) One or two bottles with accurately ground stoppers. 



(5) Pure ether. 



(6) Absolute alcohol. 



(7) Standard normal solution of soda. 



(8) Litmus solution. 



(9) Beakers. 



Process. As much of the gastric juice as can be spared, say 25 or 

 >0 c.c., is placed in the glass bottle, and there is then added to it an 

 equal volume of pure ether. This must be free from acid reaction, 

 and it must have been shaken with distilled water so as to saturate it 

 with water. 



The temperature of the liquid in the bottle is taken, and then the 

 contents are subjected to a series of vigorous agitations, which may be 

 counted ; 500 suffice. The temperature is again taken, and for prac- 

 tical purposes the mean of the two readings (i.e. of that before and 

 that after the agitation) may be taken as indicating the temperature 

 during the experiment. The bottle is then set aside for a few 

 minutes, and a measured volume, say 10 c.c., of the lower watery 

 stratum, and an equal volume of the upper ethereal solution are 

 carefully withdrawn by the aid of the two pipettes previously referred 

 to as fitted with india-rubber tubes and pinch-cocks. The acidity 



1 Bidder und Schmidt, Die Verdauungssafte und der Stqffwechsel. Mitau und 

 Leipzig, 1859, p. 44. 



