APP. V.] METHOD OF HAYEM AND WINTER. 501 



3. The Method of Hay em and Winter* for determining the free and 

 combined HCl of the gastric contents. 



The reader is referred either to the original work of Messrs 

 Hayem and Winter for a full description of their method, or to the 

 exhaustive and critical examination of it contained in Martius and 

 Luttke's book 2 . As the latter authors have very candidly pointed 

 out, the method of Hayem and Winter is based in part on a philo- 

 sophical desire not only to determine the total quantity of hydro- 

 chloric acid in the gastric contents, and the total quantity existing 

 in a free condition, but likewise the quantity which exists in organic 

 combinations. Unfortunately, however, the means employed have 

 not been adequate to the end in view and the method neither enables 

 us to determine the proportion of the free nor of the combined 

 hydrochloric acid. 



Hayem and Winter measure out 5 c.c. of the filtered gastric 

 contents into three crucibles, which we shall distinguish as a, b and c. 

 To a is added an excess of sodium bicarbonate, so as to combine with 

 the whole of the hydrochloric acid. All three crucibles are then 

 placed on the water bath and their contents ultimately dried at a 

 temperature of 100 C. The residue contained in crucible a is 

 ignited for a few minutes over a naked flame and the carbonised 

 mass is repeatedly extracted with distilled water and a little nitric 

 acid. The solution is then neutralised \vith sodium carbonate and 

 heated for some time to drive otf the carbon dioxide. 



The amount of chlorine which the solution contains is then 

 determined by means of decinormal silver nitrate solution, potassium 

 chromate being used as an indicator. From the amount of the deci- 

 normal silver solution employed, the total chlorine (' (More total ') is 

 found. 



The residue in crucible 6, after being dried, is treated with 

 concentrated solution of soda in excess and, after evaporation, the 

 residue is ignited. The amount of chlorine which it contains is then 

 determined as in the case of the residue in crucible a. By deducting 

 the amount of chlorine found in b from that found in a, Hayem and 

 Winter calculate the amount of free chlorine ('HCl libre'). 



The residue in crucible c is simply ignited and the chlorine in 

 the residue determined in the same manner as in the case of a and 

 of b. The quantity of chlorine found in c corresponds to the chlorides 

 and is designated ' Chlore fixe! 



The radical fallacy of Hayem and Winter lies in the assumption 

 that when the gastric contents are evaporated to dryness, precisely 

 the same quantity of hydrochloric acid will be volatilised as existed 

 in the free condition in the juice, a supposition which is not merely 

 theoretically improbable but, as the researches of Martius and Llittke 

 have shewn, is absolutely untrue. The total quantity of HCl can 



1 Hayem et Winter, DM Chimisme stomacal, Paris, 1891. 



2 Martius and Liittke, op. cit. pp. 94 101. 



