112 POISONS : THEIR EFFECTS AND DETECTION. [§ 83. 
hydrochloric acid or other mineral acids in a case of poisoning. It 
depends on the fact that ether extracts free organic acids, such as 
butyric and lactic acids, but does not extract mineral acids. 
The free mineral acid, after extracting the organic acid by ether, can 
also be saturated by cinchonine ; this hydrochlorate of cinchonine is 
extracted by chloroform, evaporated to dryness, and the residue dissolved 
in water acidified by nitric acid and precipitated by silver nitrate ; the 
silver chloride produced is collected on a small filter, washed, and the 
filter, with its contents, dried and ignited in a porcelain crucible ; the 
silver chloride, multiplied by 0*25426, equals HC1. 
The best method of estimating free hydrochloric acid in the stomach 
is that of Sjokvist as modified by v. Jaksch ; 1 it has the disadvantage 
of its accuracy being interfered with by phosphates ; it also does not 
distinguish between actual free HC1 and the loosely bound HC1 with 
albuminous matters : this in a toxicological case is of small importance, 
because the quantities of HC1 found are likely to be large. 
The method is based upon the fact that if carbonate of baryta be 
added to the contents of the stomach, the organic acids will decompose 
the barium caibonate, forming butyrate, acetate, lactate, etc., of barium ; 
and the mineral acids, such as hydrochloric acid, will combine, forming 
salts of barium. 
On ignition, chloride of barium will be unaffected, while the organic 
salts of barium will be converted into carbonate of barium, practically 
insoluble in carbonic acid free water. 
The contents of the stomach are coloured with litmus, and barium 
carbonate added until the fluid is no longer acid (as shown by the dis¬ 
appearance of the red colour) ; then the contents are evaporated to 
dryness in a platinum dish, and ignited at a dull-red heat ; complete 
burning to an ash is not necessary. After cooling, the burnt mass is 
repeatedly exhausted with boiling water and filtered ; the chloride of 
barium is precipitated from the filtrate by means of dilute sulphuric 
acid , the barium sulphate filtered off, washed, dried, and, after ignition, 
weighed ; 233 parts of barium sulphate equal 73 parts of HC1. 
A method somewhat quicker, but depending on the same principles, 
has been suggested by Braun. 2 A fractional part, say 10 c.c., of 
the fluid contents is coloured by litmus and titrated with decinormal 
soda. To the same quantity is added 2 or 3 more c.c. of decinormal 
soda than the quantity used in the first titration ; this alkaline liquid 
is evaporated to dryness and ultimately ignited. To the ash is now 
added exactly the same quantity of decinormal sulphuric acid as of the 
1 Klinische Diagnostilc, Dr Rudolph v. Jaksch, Wien u. Leipzig, 1892. Clinical 
Diagnosis. English translation. Fifth edition. London: Charles Griffin & Co., 
Limited. 
2 Op. cit., S. 157 
