1891.] Anaesthetic Action of Pure Nitrogen. 149 



Braine felt justified in administering the gas to patients at the Dental 

 Hospital. Nine patients took the gas. In every case, the result was the 

 production of complete anaesthesia, with general phenomena precisely 

 similar to those observed during nitrous oxide inhalation. The pulse 

 was first full and throbbing, then feeble ; in the advanced stage 

 respiration was deep and rapid, with lividity of the surface, dilated 

 pupils, and more or less jactitation of the limbs ; the only difference, 

 in the opinion of some of those present, being that the anaesthesia was 

 less rapidly produced, and somewhat less durable than that from 

 nitrous oxide, though in each case the tooth was extracted without 

 pain. 



On a subsequent occasion, the same gas was administered by 

 Dr. Frederic Hewitt at the Dental Hospital. Nine patients took 

 the gas. The maximum period required to produce anaesthesia 

 was 70 seconds, the minimum 50 seconds, and the mean time 

 58'3 seconds. 



In one case, two teeth were extracted without pain ; in one only 

 ras pain experienced, and in that case, the tooth having been broken 

 and not extracted, the patient said she felt a " smashing up." 



I subsequently obtained from the same Company a cylinder con- 

 taining compressed nitrogen with 3 per cent, of oxygen, and a second 

 cylinder containing nitrogen with 5 per cent, of oxygen. These gases 

 were also administered by Dr. Hewitt to patients at th.3 Dental 

 Hospital, with the following results. 



. Five patients took the 3 per cent. gas. Anaesthesia was complete in 

 75 seconds (max.), and in 60 seconds (min.J, the average time 

 required being 67'5 seconds. In each case, the tooth was extracted 

 without pain, the duration of anaesthesia being somewhat longer than 

 with pure nitrogen. In ea,ch case there was lividity, dilatation of 

 pupils, and more or less jactitation. 



Four patients took the nitrogen containing 5 per cent, of oxygen. 

 With this mixture, the time required for the production of anaesthesia 

 ranged from 75 to 95 seconds, the average time being 87'5 seconds. 



In each case there was complete anaesthesia, during which one 

 patient had three molars extracted. Although she said she felt the 

 last two, the sensation appeared to be that of a pull, and not of acute 

 pain. 



. In most of these four cases there was slight lividity before the 

 removal of the face-piece. In only one case was there slight jactita- 

 tion of the limbs ; the other three patients were perfectly quiescent. 



For the information of those who may be disposed to investigate 

 the anaesthetic action of nitrogen with a small proportion of oxygen, 

 may mention that Erin's Oxygen Company (69, Horseferry Road, 

 Westminster) are prepared to supply nitrogen containing from 4 to 7 

 cent, of oxygen at the same rate as they charge for pure oxygen. 



