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neSs. The most severe experiments of this nature are those carried out 

 by Haldane and his colleagues. Ons experiment in particular demands 

 attention. Dr. Haldane and Dr. Ivellas^ together spent an hour in 

 a chamber in which the air was reduced to between 320 and 295 mm. 

 It is difficult to say how far they were conscious. Clearly each 

 believed the other to be complete master of liis own faculties, but it is 

 evident that Dr. Haldane was not so. I gather that he has no recollec- 

 tion of what took place, that whenever he was consulted about the 

 pressure he gave a stereotyped answer which was the same for all 

 questions, that, even with a little more oxygen present, he was suffi- 

 ciently himself to wish to investigate the colour of his lips in the glass, 

 but insufficiently himself to be conscious that he was looking into the 

 back and not the front of the mirror. Dr. Kellas, who could make 

 observations, never discovered Dr. Haldane's mental condition, though 

 boxed up with him tor an hour, and went on consulting him auto- 

 matically. A somewhat similar experiment was performed on the other 

 two observers, with results differing only in degree. 



Yet the after-effects are summed up in the following sentence : 

 ' All four observers suffered somewhat from headache for several hours 

 after these experiments, but there was no nausea or loss of appetite.' 



Of real importance in this connection are the results of carbon 

 monoxide poisoning. Of these a large number might be cited. Those 

 interest-ed will find some very instructive cases described in a volume 

 entitled ' The Investigation of Mine Air,' by the late Sir 0. he Neve 

 Foster and Dr. Haldane.* The cases in question were those of a 

 number of officials who went to investigate the mine disaster on 

 Snaefell, in the Isle of Man, in May 1897. Of the five cases cited all 

 suffered some after-effects, by which I mean that by the time the blood 

 was restored sufficiently to its normal condition for the tissues to get 

 the amount of oxygen which they required, the effects of the asphyxia 

 had not passed off and to this extent the machine suffered, e.g. 



Mr. W. H. Kitto says : ' On reaching terra firma I felt very ill and 

 wanted to vomit . . . through the night. I had severe palpitation of the heart, 

 a thing I have never felt in my life before or since. On the day following, 

 Thursday, the pain in my knees was so great that I could not stand properly, 

 and for fully a week 1 had gi'eat pain when walking, and still (a month 

 later) feel slight effects of the poisoning.' 



Of the five whose experiences were given, the one who received the 

 most permanent damage was Sir Clement Foster himself. 



A few days after I got back from the island the first time, about the 

 21st or 22nd of May, I noticed my heart ; it could scarcely be called palpitation, 

 as I understand palpitations to be, for there did not seem to be any increased 

 rapidity of the action, but I was conscious of its beating; as a rule, I am not. 

 This passed off, and then on the 1st and 2nd of June I noticed it very decidedly 

 again, so much so that I went to my doctor. He sounded me, and said the 

 heart was all right, though there was one sound which was not very distinct. 

 This consciousness of having a heart still returns from time to time, though 

 only to a slight extent. On the 19th May I suffered much from headache, not 

 regularly, but intermittently. The headache lasted for several days, and the 

 feeling in the legs was very apparent ; it was an aching in the legs ' from the 

 knees to the ankles. A coldness from the knees to the solee of the feet 

 wa« also noticeiaible ; it came on occasionally for a considerable time. The 



