APP. v.] LUTTKE'S METHOD. 505 



would decompose the HCl, liberating chlorine ; and the results of the 

 analysis would be vitiated. 



Whether permanganate has to be added or not, the contents of 

 the flask are diluted with distilled water to the 100 c.c. mark, and 

 then filtered, through a dry filter, into a dry vessel. 50 c.c. of the 

 filtrate are now measured into a beaker, and the amount of 

 silver which they contain determined by means of the decinormal 

 sulphocyanate solution. The number of cc. used is multiplied by 

 two, and the product subtracted from the volume of silver solution 

 employed (i.e. 20 c.c.) gives us the amount of silver required to com- 

 bine with the total chlorine, and therefore the amount of the latter 

 in 10 c.c. of the gastric contents. 



b. Determin- 10 c.c. of the mixed gastric contents are evaporated 



^ to dryness in a platinum capsule on the water bath, 

 mineral com- -^ n tne absence of a water bath, the capsule may be 

 bination. placed on an asbestos slab, which is heated by means 



of a gas or spirit-lamp flame, a substitute which per- 

 mits of the liquid being dried without spurting and therefore without 

 loss. When the residue is dry, it is ignited over the naked lamp, 

 until the carbonised residue no longer burns with a luminous flame, care 

 being taken not to ignite the capsule strongly, as chlorides are 

 volatile at a strong red heat. 



After the incineration, the residue is moistened and pounded by 

 means of a glass rod ; it is treated successively with hot water (in all 

 about 100 c.c.), and the solution is filtered. Care must, necessarily, 

 be taken to ascertain that the whole of the chlorides have been 

 extracted from the carbon. The whole filtrate is then precipitated 

 in a beaker with 10 c.c. of decinormal silver solution, and the excess 

 of silver determined by means of the decinormal sulphocyanate solu- 

 tion. By subtracting the volume of the latter required, from the 

 volume of the silver solution taken (i.e. 10 c.c.) we find the amount 

 of pure silver required to combine with the chlorine in the chlorides 

 of the incinerated gastric contents. 



Calculation of From the two values (total chlorine a and chlorine 

 the hydrocMo- of chlorides 6) we ascertain the amount of the total 

 ' acid present in 10 c.c. of the stomach contents by a 

 simple subtraction. If we multiply the number thus found (the 

 difference) by 0'0365, we obtain the absolute amount of hydrochloric 

 acid in 100 c.c. of the contents of the stomach. 



