132 POISONS : THEIR EFFECTS AND DETECTION. [§§ 122-126. 
tlie precipitate is collected on a tared filter and weighed, after drying at 
100°. In this way the analyst both distinguishes between the salts of 
sodium and potassium, and estimates the relative quantities of each. It 
is hardly necessary to observe that, if the double chloride is wholly 
soluble in water or alcohol, sodium alone is present. This, however, will 
never occur in operating on organic tissues and fluids, for both alkalies 
are invariably present. A correction must be made when complex organic 
fluids are in this way treated for alkalies which may be naturally in the 
fluid. Here the analyst will be guided by his preliminary titration, 
which gives the total free alkalinity. In cases where the alkali has been 
neutralised by acids, of course no free alkali will be found, but the corre¬ 
sponding salt. 
VII.—Neutral Sodium, Potassium, and Ammonium Salts. 
§ 122. The neutral salts of the alkalies are poisonous, if administered in sufficient 
doses, and the poisonous effect of the sulphate, chloride, bromide, iodide, tartrate, 
and citrate appears to depend on the specific action of the alkali metal, rather than 
on the acid, or halogen in combination. According to the researches of Dr Ringer 
and Dr Harrington Saintsbury, 1 with regard to the relative toxicity of the three, 
as shown by their effect on the heart of a frog—first, the potassium salts were found 
to exert the most poisonous action, next come the ammonium, and, lastly, the sodium 
salts. The highest estimate would be that sodium salts are only one-tenth as 
poisonous as those of ammonium or potassium ; the lowest, that the sodium salts 
are one-fifth : although the experiments mainly throw fight upon the action of the 
alkalies on one organ only, yet the indications obtained probably hold good for the 
organism as a whole, and are pretty well borne out by clinical experience. 
There appear to be four cases on record of poisoning by the above neutral salts ; 
none of them belong to recent times, but fie between the years 1837-1856. Hence, 
the main knowledge which we possess of the poisonous action of the potassium salts 
is derived from experiments on animals. 
§ 123. Sodium Salts. —Common salt in such enormous quantity as half a pound 
to a pound has destroyed human fife, but these cases are so exceptional that the 
poisonous action of sodium salts is of scientific rather than practical interest. 
§ 124. Potassium Salts. —Leaving for future consideration the nitrate and the 
chlorate of potassium, potassic sulphate and tartrate are substances which have 
destroyed human fife. 
Potassic Sulphate (K 2 S0 4 ) is in the form of colourless rhombic crystals, of bitter 
saline taste. It is soluble in ten parts of water. 
Hydropotassic Tartrate (KHC 4 H 4 0 6 ), when pure, is in the form of rhombic 
crystals, tasting feebly acid. It is soluble in 210 parts of water at 17°. 
§ 125. Action on the Frog’s Heart. —Both excitability and contractility are 
affected to a powerful degree. There is a remarkable slowing of the pulsations, 
irregularity, and, lastly, cessation of pulsation altogether. 
§ 126. Action on Warm-blooded Animals. —If a sufficient quantity of a 
solution of a potassic salt is injected into the blood-vessels of an animal, there is 
almost immediate death from arrest of the heart’s action. Smaller doses, sub¬ 
cutaneously applied, produce slowing of the pulse, dyspnoea, and convulsions, ending 
in death. Small doses produce a transitory diminution of the foice of arterial 
pressure, which quickly passes, and the blood-pressure rises. There is at first, for 
a few seconds, increase in the number of pulsations, but later a remarkable slowing 
1 Lancet, June 24, 1882. 
