PHYSIOLOGICAL ACTION OF OKGANIC CHEMICAL COMPOUNDS, 151 



anffisthesia ; in all cases there is sudden and extreme decrease of the animal 

 temperature. In birds, rabbits, guineapigs, as well as in the human subject, 

 tlieso phenomena are observable. But there are other symptoms belonging 

 to bromal hydrate which are peculiar to it, and Avhich render its practical 

 ntihty, according to our present knowledge of it at any rate, doubtful. It is 

 intensely irritating ; it causes great difficulty of respiration ; it so suddenly 

 and effectually reduces the animal temperature that the accumulation of fluid 

 in the bronchial canals, from condensation, is a source of positive danger, 

 and altogether its internal employment would be unwise. I agree with 

 Drs. Steinann and DougaU as to the mode of its action, and, with them, 

 attribute the phenomena to the effects of the bromoform that is liberated in 

 the body after the dose has been administered ; I agree also with Dougall 

 that the cause of death, when the dose is fatal and slow, is due to asphyxia. 

 I attribute the asphyxia primarily to the fall of temperature of the body, and 

 secondarily to condensation of water in the bronchial passages. 



One condition I have noticed which seems not to have fallen under the 

 attention of the learned observers I have named, viz. that in bii'ds a large 

 dose of the bromal hydrate may destroy life almost instantaneously by 

 an intense convulsion, amounting, in fact, to suddenly developed tetanus. 



The chief interest at this moment attaching to bromal hydrate is the dif- 

 ference that is seen in its action, in comparison with the action of chloral 

 hydrate. It illustrates how a difference of chemical elementary constitution 

 and of weight modifies physiological action ; how the heavier bromine in 

 combination with carbon, hydrogen, oxygen, and water differs in action 

 from chlorine in similar combination. The science of therapeutics will ulti- 

 mately rest on these distinctions. 



NlTEITE OF AmTL. 



At the Meeting of the Association held at Newcastle-on-Tyne in 1863, I 

 introduced this curious and potent substance to the notice of the Association, 

 and explained, as best I could, its history and its physiological properties. 

 Every year since then some new fact of interest has attached to the sub- 

 stance, and the immediate past year is not different in this respect from 

 those that have preceded it. The first observer of the action of nitrite of 

 amyl on the animal functions was Professor Guthrie, P.E.S., then of Edin- 

 burgh, and now of the School of Mines, London. Professor Guthrie observed, 

 while working in the laboratory with nitrite of amyl, that the inhalation of 

 its vapour produced flttshing of the face, rapid action of the heart, a peculiar 

 breathlessness, such as occurs after fast running, and disturbance of cerebral 

 action. These facts, most ably described by the^ Pi'ofessor, became known 

 to Mr. Morison, a dentist in Edinbttrgh, who thought from them that the 

 substance might be made of service for the treatment of persons who were 

 suffering from faintness. He therefore brought some of the compound to 

 the College of Dentists, a Society then existing in London, and the Council 

 of that institution referred the whole subject to mo, with a request that I 

 would report to them. The task was readily undertaken, and the study con- 

 nected with it has not been completed at this hour. 



I take the liberty of mentioning these details for the sake of historical 

 accuracy. From the circumstance that I have introduced nitrite of amyl 

 greatly into medical practice, and have been year after year treating of its 

 action, it has been all but universally believed that I made the earliest 

 observations upon it; I would correct this error : I have worked industriously 

 with nitrite of amyl, have studied careftilly its mode of action, and have sug- 



