PHYSIOLOGICAL ACTION OF THE METHYL AND ALLIED SERIES. 411 



reduction of temperature ; but from this he would recover, if there were no 

 other conditions acting injuriouslj- at the same time. It is fair, therefore, to 

 assume that in the atmosphere which generates malarial fever, the hj-diile is 

 only a coincident with the true cause of fever, and that either dampness or 

 the presence of some other organic poison is at work to jn'oduce the more 

 serious and persistent consequences of exposure to marsh-air. 



Hydride of methyl in the pure state might be used as nitrous oxide is 

 often used, viz. to produce insensibility to pain by gaseous suffocation ; but 

 the principle of the method is rude and unworthy of science. 



Hydride of Amyl. — Hydride of amyl may be made by adding iodide of amyl 

 to water with zinc, and applying heat at 288° F. ( = 142|° C.) for some hours. 

 On distillation a fluid comes over composed of amyleue and the hydride ; the 

 mixture is left in contact with caustic potassa for twenty-four hours, and is 

 then rectified from a water-bath at 35° C. The distillate is immersed in a 

 freezing-mixture, and treated witli anhydrous and fuming sulphuric acid, 

 which retains the amylene, and the hydride is distilled over. This, which is 

 Franldand's process, is described in full in Watts's Chemical Dictionary ; 

 but to get by this plan any sufficient quantity of fluid for a series of physio- 

 logical researches vs'ould bo practically out of the question. Fortunately the 

 hydride forms one of the parts of American petroleum, and from a specimen 

 of this petroleum Dr. Yersmann has been able to distil for me a sufficient 

 quantity of the fluid for my purposes. The specimen presents all the cha- 

 racteristics of the hydride ; the specific gravity is 0-G2.5, and it boils at 

 86° F. (=30° C). As a fluid it is colourless and odourless ; it is very agreeable 

 to breathe, and creates no irritation. There is a specimen before the Section. 



A distillation from petroleum, having all the properties of hydride of amyl, 

 was tried in America about two years ago as a general anaesthetic, and was 

 reported on favourably. I therefore subjected the hydride to careful experi- 

 ment, and foiind it to be truly a general anaesthetic that might admit of 

 practical application. In order to produce decided effects, 40 per cent, of the 

 vapoiar of the hydride must be present in the inspired air ; and so volatile is 

 the fluid that constant repetition of it is necessary, unless it be placed in a 

 receiver admitting very little air. Administered by inhalation to pigeons, in 

 sufficient quantity to produce determinate insensibilitj', the period required 

 for the pi'oduction of symptoms was found to be under a minute, and the in- 

 sensibility to be profound in a period a little less than two minutes. The 

 insensibility in the bird is attended with some convulsive movement and 

 dra-wing back of the head. Eecovery from the eflfects of the hydride is 

 rapid, not so rapid as in the case of the hydride of methyl, but still rapid, the 

 animal regaining its full consciousness and muscular power within two 

 minutes. The temperature of the body remains nearly unchanged. The 

 inclination is towards a reduction of temperature, but it does not exceed the 

 fourth of a degree on Fahrenheit's scale. The blood undergoes no obvious 

 change. 



To observe the extreme effects of the hydride, animals, after they had be- 

 come insensible, were allowed to sleep into death. The process of death is 

 gentle, and the respiration and circulation cease nearly simultaneously, the 

 respiration failing a little first. The temperature of the body falls during the 

 last few minutes of life from 1° to ] |° of Fahrenheit's scale. The pupil 

 dilates. After death the heart is found well charged with blood on both 

 sides, and the organ on exposure to the air starts into vigorous action. The 

 blood on the left side is darkened in colour, but the coagulation is natural, and 

 the corpuscles are uninfluenced. The lungs, as is common when both sides of 



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