TlUME THYLAMIN. 1 6 7 



and then depressed, leading to weak respirations with long 

 pauses, dyspnoea, convulsions, and finally death by asphyxia. 

 Simultaneously, the afferent branches of the respiratory nerves 

 are depressed, especially if the acid be inhaled ; and reflex 

 respiratory acts are arrested. The vaso-motor centre is tem- 

 porarily stimulated, and the blood pressure rises, but it falls 

 again suddenly and greatly. The cardiac centre is the most 

 resistant of the three, but it also is depressed, so that the 

 action of the heart becomes less frequent and powerful. 

 Although at the same time the nervo-muscular structures of 

 the heart are depressed, the heart continues to beat in 

 animals poisoned with prussic acid, after the respiration and 

 other functions have- ceased. The convolutions are depressed, 

 causing stupor, ending in unconsciousness ; but this effect may 

 be secondary to the disturbance of respiration. The cord is 

 also lowered in activity. The peripheral sensory nerves are but 

 little affected by the internal use of the drug, compared with 

 its effect upon them locally. The motor nerves and muscles are 

 depressed by repeated small doses of dilute hydrocyanic acid, 

 the influence extending downwards. 



The chief specific use of this drug is to allay dry, useless 

 cough, by its action on the respiratory centre and the afferent 

 nerves, in phthisis, pertussis, and asthma. In phthisis it also 

 checks the tendency to cough and vomit induced by food. 

 As a cardiac sedative, it is employed in the palpitation, pain, 

 and distress brought on by dyspepsia, where again it fulfils a 

 double indication. Its general sedative effect on the nervous 

 s\ >{' in has suggested its use in epilepsy, chorea, hysteria, and 

 tetanus, but with very doubtful benefit. 



4. REMOTE LOCAL ACTION. 



The mode of excretion of hydrocyanic acid is still ob- 

 scure. Probably it escapes in part, as it enters in part, by the 

 lungs ; and some of it is supposed to be thrown out as formate 

 of ammonia. 



TRIMETHYLAMIN. PROPYLAMIN. (Not Officinal) 



An ammonia compound, in which the thre 

 atoms of hydrogen are replaced by methyl, NC 3 H 9 = 

 N(CH 3 ) 3 , dissolved in water. 



Source. Obtained from herring brine by distillation. It is 

 also contained in cod-liver oil and in various plants. 



Characters. Trimethylamin contains 10 to 20 per cent, of 

 the ammonia compound ; is colourless, with a very disagreeable 



