§§ 120, 121.] CAUSTIC POTASH AND SODA. 131 
a case related by Dr Tunstall, 1 a man for eighteen years had taken 
daily 2 ozs. of bicarbonate of soda for the purpose of relieving indigestion. 
He died suddenly, and the stomach was found extensively diseased ; 
but since the man, before taking the alkali, had complained of pain, etc., 
it is hardly well, from this one case, to draw any conclusion. 
It is important to observe that the contents of the stomach may be 
acid, although the death has been produced by caustic alkali. A child 
aged 4 drank from a cup some 14 per cent, soda lye. He vomited 
frequently, and died in fifteen hours. The stomach contained 80 c.c. of 
sour-smelling, turbid fluid, the reaction of which was acid. There were 
haemorrhagic patches in the stomach, and signs of catarrhal inflamma¬ 
tion ; there was also a similarly inflamed condition of the duodenum. 2 
§ 120. Chemical Analysis. —The tests for potassium or sodium are 
too well known to need more than enumeration. The intense yellow 
flame produced when a sodium salt is submitted to a Bunsen flame, and 
the bright sodium-line at D when viewed by the spectroscope, are 
delicate tests ; while potassium gives a dull red band in the red, and a 
faint but very distinct line in the violet. Potassium salts are precipi¬ 
tated by tartaric acid, while sodium salts do not yield this precipitate ; 
potassium salts also give a precipitate with platinic chloride insoluble 
in strong alcohol, while the compound salt with sodium is rapidly 
dissolved by alcohol or water. This fact is utilised in the separation 
and estimation of the two alkalies. 
§ 121. Estimation of the Fixed Alkalies. —To detect a fixed alkali 
in the contents of the stomach, a convenient process is to proceed by 
dialysis, and after twenty-four hours, to concentrate the outer liquid 
by boiling, and then, if it is not too much coloured, to titrate directly 
with a decinormal sulphuric acid. After exact neutralisation, the liquid 
is evaporated to dryness, carbonised, the alkaline salts lixiviated out with 
water, the sulphuric acid exactly precipitated by baric chloride, and then, 
after separation of the sulphate, the liquid treated with milk of lime. 
The filtrate is treated with a current of C0 2 gas, boiled, and any pre¬ 
cipitate filtered off ; the final filtrate will contain only alkalies. The 
liquid may now be evaporated to dryness with either hydrochloric or 
sulphuric acid, and the total alkalies weighed as sulphates or chlorides. 
Should it be desirable to know exactly the proportion of potassium to 
sodium, it is best to convert the alkalies into chlorides—dry gently, 
ignite, and weigh ; then dissolve in the least possible quantity of water, 
and precipitate by platinic chloride, which should be added so as to be a 
little in excess, but not much. The liquid thus treated is evaporated 
nearly to dryness, and then extracted with alcohol of 80 per cent., which 
dissolves out any of the double chloride of platinum and sodium. Finally, 
1 Med. Times , Nov. 30, 1850, p. 564. 
2 Lessor, Atlas d. gericht. Med. t Tafel ii. 
