432 PRUSSIC ACID 



minutes, and death is preceded by giddiness, impaired 

 voluntary movement, dilatation of the pupil, a slight rise 

 and subsequent fall of blood-pressure, slowing of the pulse, 

 rapid failure of respiration, and tetanic convulsions. The 

 heart continues to beat for several minutes after respiration 

 has ceased. Experimentally, two ounces were found to 

 cause rapid death of Greenland whales, when discharged by 

 an ingenious device into the wound made by the harpoon. 



Post-mortem discloses variable appearances. Animals 

 dying almost instantaneously from cardiac arrest have the 

 blood of an arterial hue, as if, from dilatation of the remote 

 capillaries, it had passed through them without change, 

 When the respiratory centre of the medulla has been 

 paralysed, causing death somewhat more slowly by respira- 

 tory arrest, the appearances are those of suffocation. For 

 some hours after death the blood remains fluid, of a blue 

 colour, and occasionally evolves the peculiar odour of the 

 acid. 



ANTIDOTES. Prussic acid is usually so rapidly fatal that 

 the animal is often dead before any remedial measures can 

 be adopted ; but so volatile is the poison, and so rapidly is 

 it removed from the body, chiefly by the lungs, that if the 

 animal lives for half an hour it will generally recover. 

 Artificial respiration, and subcutaneous injection of ether, 

 sometimes save animals that have had lethal doses. Cautious 

 hypodermic injection of small doses of atropine sulphate 

 stimulates the cardiac and respiratory centres, and may 

 thus avert mortal paralysis. Inhalation of ammonia and 

 douching alternately with cold and warm water applied to 

 the head and neck, have also been advised. The chemical 

 antidote is a mixture of a ferrous and ferric salt, administered 

 with magnesia or potassium carbonate, and forming the in- 

 soluble Prussian blue. But to be effectual the antidote must 

 be swallowed before the rapidly-acting poison is absorbed. 



MEDICINAL USES. By paralysing the ends of the sensory 

 nerves, the acid allays the irritation of urticaria, prurigo, 

 and other itching skin complaints. In like manner it some- 

 times relieves gastrodynia and chronic vomiting, being con- 

 joined in such cases with ice, bismuth, and morphine ; while 

 in irritable conditions of the throat it is prescribed with 



