500 METHOD OF SJOQVIST. [BOOK II. 



foot-note, p. 93), has been simplified by McNaught 1 , though according 

 to Martius and Liittke the modifications only increase the chances of 

 error attaching to the original method. 



2. The Method of Sjdqvist* modified by v. Jaksch 3 of determining 

 the total HGl in the stomach contents. 



This method rests upon the fact that when gastric juice or the 

 contents of the stomach are evaporated to dryness with barium 

 carbonate, the free acids combine with barium. On igniting the 

 residue, the organic barium salts furnish insoluble barium carbonate, 

 whilst the chloride of barium formed by the hydrochloric acid of the 

 gastric juice is soluble in water, which may be used to extract it. 



10 c.c. of unfiltered stomach contents are measured into a plati- 

 num or nickel capsule, and a drop of tincture of litmus is added. 

 Absolutely pure barium carbonate (i.e. absolutely free from chlorine) 

 is then added, until the mixture is no longer red, care being taken 

 not to add an unnecessary excess of the barium salt. The capsule is 

 now heated to dryness on the water bath, in an atmosphere free from 

 HC1. The capsule is then ignited until all the organic matters are 

 destroyed, and the residue is repeatedly extracted with boiling water 

 and the solution filtered. The volume of the clear filtrate should 

 not exceed 80 100 c.c. The quantity of barium which it contains 

 should then be determined gravimetrically by precipitation with 

 dilute sulphuric acid, &c. The quantity of barium sulphate multi- 

 plied by 0'3132 gives the amount of HC1 present in 10 c.c. of the 

 gastric juice. The control determinations made by v. Jaksch have 

 shewn that, as carried out by him, the method is one of great exacti- 

 tude. The method would appear to be theoretically a very perfect one 

 if the barium determination be carried out gravimetrically by an 

 experienced worker. Martius and Liittke have, however, found that 

 when the quantity of free HC1 is small and the greater part of the 

 acid is in combination with albuminous substances, the results 

 obtained by Sjoqvist's method are frequently much below the truth. 

 They believe that this may depend upon an imperfect decomposition 

 of the acid albuminous compound and suggest that by diluting the 

 mixture of gastric juice and barium carbonate and gently heating it 

 the difficulty may be got over*. 



1 McNaught, Medical Chronicle, March, 1887. The Author has not had the 

 opportunity to see the original paper. 



. 2 Sjoqvist, 'Eine neue Methode, freie Salzsaure im Mageninhalte quantitativ zu 

 bestimmen,' Zeitsch. f. phys. Che'mie, Vol. xm. p. 1. 



3 v. Jaksch, ' Zur quantitativen Bestimmung der freien Salzsaure im Magensafte, ' 

 Monatshefte f. Chem. Vol. x. (1889), pp. 211213. 



4 Martius and Liittke, pp. 85 and 86. 



