PHYSIOLOGICAL ACTION OF ORGANIC CHEMICAL COMPOUNDS. 159 



fluid, in vapour, forty-six times for short operations on the liuman subject, 

 and in tlie average of cases have produced the required insensibility within 

 fifty seconds. In one instance insensibility was produced, a firm tooth was 

 extracted, and perfect recovery occurred in forty seconds. As yet there has 

 neither been vomiting nor other untoward symptom during the adminis- 

 tration. 



There is, however, a peculiarity in the action of this vapour to which I 

 ought carefully to refer, viz. that insensibility from it intensifies after the 

 inhalation of it is withdrawn. Thus in administering, whenever there is the 

 least indication of its effects, such as winking of the eyelids or drop of the 

 hand, the sigu is given to stop the administration. The operator may now 

 wait a few seconds and then proceed. The inhaler I have constructed for 

 the administration of this new anesthetic is before the Meeting. It is a simple 

 hollow cone made of leather, and is furnished with two light silken valves 

 for entrance of air and exit of vapour and breath. It is lined with domctte 

 set on a light frame or ring of metal. "When the inhaler is not in use it 

 forms a ease for holdiug safely, in a bottle, four fluid-ounces of the anaesthetic 

 liquid. This quantity is sufiicient for twenty operations, of from one and a 

 half to three minutes' duration, two drachms being the amount necessary 

 for an operation not exceeding three minutes' duration. 



The vapour described above will become, I believe, should experience 

 confirm its safety, of general apphcation as an anaesthetic for short opera- 

 tions; for long operations it will probably not replace the heavier anajsthetics. 



1 am indebted to Mr. Ernest Chapman for the suggestion of the abbreviated 

 name hydramyle. 



PHYSIOLOGICAL NOTES. 



In the course of the researches detailed in the preceding pages I have again, 

 as in iirevious researches, been led to notice certain simple facts which lie in 

 the path of inquiry, and which, though not necessarily belonging to it, are 

 too prominent to be passed by without notice. I shall therefore offer a few 

 notes bearing on three topics ;] and this the more readily, because it is rarely 

 the case that so many eminent physiologists as are now present, each one 

 interested in the subjects to be named, meet together to take part in dis- 

 cussion. 



Effect of some Karcotic Vapotjes on tee mintjte cieculation of the Biood, 



I have taken occasion several times to observe the effect of narcotic vapours 

 on the minute circulation of the blood. I prefer to use the term " minute 

 circulation " because it embraces the minute arterial and venous, as well as 

 the capillary circulation. 



In these researches the web of the foot of the frog was selected for obser- 

 vation, and I think on the whole with advantage. The following particulars 

 were carried out in every case : — 



. (a) A large healthy frog was chosen, and one in which the web was very 

 clear. (6) The same microscopic power, and that low — the inch or half-inch 

 object-glass and A e}'e-piece (Ross) — was always employed, (c) The tempera- 

 ture of the air was kept the same during periods of observation, and the work 

 was conducted during the same hours each day, viz. between the hours of 



2 and 5 p.m. (d) The observations were never hurried ; they occupied an 

 average of three hours each, and every change of scene in the vessels through 

 the various stages of narcotism and of recovery were carefully and systema- 



