§ 142.] DETECTION OF ALKALI SALTS. 137 
if the analyst obtains a response to the test, he will naturally confirm or disprove it 
by the following process :— 
The liquid under examination, organic or otherwise, is divided into two equal 
parts. In the one, all the chlorine present is precipitated as chloride by silver 
nitrate in the usual way, and the chloride of silver collected and weighed. In the 
other, the liquid is evaporated to dryness and well charred by a dull-red heat, the 
ash dissolved in weak nitric acid, and the chlorides estimated as in the first case. If 
chlorates were present, there will be a difference between the two estimations, pro¬ 
portionate to the amount of chlorates which have been converted into chlorides by 
the carbonisation, and the first silver chloride subtracted from the second will give 
an argentic chloride which is to be referred to chlorate. In this way also the amount 
present may be quantitatively estimated, 100 parts of silver chloride equalling 854 
of potassic chlorate. 
Toxicological Detection of Alkali Salts. 
(See also ante, p. 131.) 
§ 142. Sodium, in combination, especially with chlorine, and also with sulphuric, 
carbonic, and phosphoric acids, is found in the plasma of the blood, in the urinary 
secretion, in the pancreatic juice, in human bile, and in serous transudations, etc. 
Potassium, in combination, is esp'ecially found in the red blood corpuscles, in the 
muscles, in the nervous tissues, and in milk. Ammonia, in combination with acids, 
is naturally found in the stomach, in the contents of the intestine ; it is also a 
natural constituent of the blood in small traces, and in a corpse is copiously evolved 
from putrefactive changes. 
It hence follows that mere qualitative tests for these elements in the tissues or 
fluids of the body are not of the slightest use, for they are always present during the 
life of the healthiest individual, and can be found after death in persons dying from 
any malady whatever. To establish the fact of a person having taken an unusual 
dose of any of the alkali salts, by simply chemical evidence, it must be proved that 
the alkalies are present in unusual quantities or in an abnormal state of combination. 
In cases of rapid death, caused by sodic or potassic salts, they will be found in 
such quantity in the contents of the stomach, or in matters vomited, that there will 
probably be no difficulty in coming to a direct conclusion ; but if some time has 
elapsed, the analyst may not find a sufficient ground for giving a decided judgment, 
the excretion of the alkali salts being very rapid. 
In most cases, it will be well to proceed as follows :■—The contents of the stomach 
are, if necessary, diluted with distilled water, and divided into three parts, one of 
which is submitted to dialysis, and then the dialysed liquid evaporated to a small 
bulk and examined qualitatively, in order to ascertain whether a large amount of 
the alkaline salts is present, and in what form. In this way, the presence or absence 
of nitrate of potassium or sodium may be proved, or the iodide, bromide, sulphate, 
and chlorate detected. 
To find, in this way, nitrate of potassium, a coarse test is preferable to the finer 
tests dependent upon conversion of the nitrate into nitrites or into ammonia, for 
these tests are so delicate that nitrates may be detected in traces ; whereas, in this 
examination, to find traces is of no value. Hence, the old-fashioned test of treating 
the concentrated liquid in a test tube with copper filings and then with sulphuric 
acid, and looking for the red fumes, is best, and will act very well, even should, as 
is commonly the case, some organic matters have passed through the dialyser. 
Chlorates are indicated if the liquid is divided into two parts and tested in the 
manner recommended in the previous section. If present in any quantity, chlorates 
or nitrates may be indicated by the brilliant combustion of the organic matter when 
heated to redness, as also by the action of strong sulphuric acid on the solid sub¬ 
stances—in the one case, yellow vapours of peroxide of chlorine being evolved; in 
the other, the red fumes already mentioned of nitric peroxide. 
With regard to a substance such as the hydro-potassic tartrate, its insolubility in 
