158 REPORT 1871. 



less pungent than vapour of chloroform, but still pungent ; the vapour burns 

 in air. The specific gravity of the fluid is 1-174, the vapour-density 49, the 

 boiling-point 64= C. (149° F.). The composition is C, H, Cl^. It differs 

 from Dutch liquid, which in other respects it resembles, in not being de- 

 composed by an alcoholic solution of potassa (Snow). 



I had already seen chlor-ethylidene in use in 18.52, and had added Snow'a 

 memoir upon it (during the writing of which, by the way, he was taken with 

 his fatal seizure) in my edition of his works on anoesthesia, published in 

 1858 ; but since the subject has come up again I have travelled once more 

 over the same ground. I obtained a specimen of chlor-ethylidene, adminis- 

 teredlt several times for the production of antesthesia, and am bound to say 

 of it that it is a very good autcsthetic. It resembles bichloiide of methylene 

 very much in its action, produces vomiting as rarely, but is less rapid than 

 the bichloride, being of higher boiling-point and yielding a heavier vapour. 



On inferior animals I find that when carried to extremity it arrests the 

 respiration before it arrests the action of the heart ; and I also find that 

 recovery from its cxtremest effects is comparatively easy. In one of my 

 lectures during the past winter session I restored life in a rabbit, by careful 

 artificial respiration, seven minutes and a half after all signs of natural re- 

 spiration had been abolished by the vapour of chlor-ethylidene. 



I would give to chlor-ethylidene a prominent place amongst anaesthetics. 

 It would take the place of either chloroform or bichloride of methyleno 

 efiiciently ; it is safer than chloroform, and excites vomiting less frequently ; 

 it is less rapid in action than methylene bichloride, not more effective, and 

 possesses, I think, about the same value in matter of safety. 



Htdeamtle. 



At the Meeting of the Association at Exeter I placed before this Section a 

 fluid called hydride of amyl. The fluid had a specific gTa^dtv of -G^.^, and it 

 boiled at 30° C. (86° F.). Its composition was stated to be C, H^^ H. I de- 

 scribed then that this vapour was a quickly acting autesthetic. 



During the present year I have experimented largely again with this 

 hydride, vdth the view of rendering it applicable for the production of rapid 

 autesthetic sleep, for short operations, such as extraction of teeth. In 

 this research I found one or two difiiculties in the way. The fluid was 

 too light to be manageable on every occasion ; that is to say, it escaped 

 from the inhaler, as a gas, by the mere warmth of the breath, and the vapour 

 had also an odour which to the majority of persons was objectionable. 



I set to work to obviate these difficulties, first by slightly weighting the 

 fluid, and secondly by making an inhaler that should more effectually restrain 

 the liquid as it was undergoing evaporation. In both attempts I have suc- 

 ceeded well. 



In making good bichloride of methylene we put finely pulverized zinc into 

 a retort and pour upon it absolute alcohol and chloroform, using afterwards 

 a heat not exceeding 120° F., in order to distil over the product. I modified 

 this process by diluting the mixture of chloroform and alcohol with eight times 

 the volume of hydride of amyl. This mixture is poured upon the zinc, 

 ■with the result of an instant vehement action Avithout any application of 

 heat; after a free evolution of gas, which lasts some minutes, there dis- 

 tils by this method a fluid which contains pure hydride of amyl and pure 

 bichloride of methylene. If the distillation be carried on at 98° F., the fluid 

 that comes over has the specific gravity of ordinary ether (-720), a most 

 agreeable odour, and rapid anaesthetic action. I have now administered this 



