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Chapter XIII 



subjective methods should be treated statistically. Each observation 

 takes but a few seconds and does not affect the composition of the 

 fluid observed. With a given sample of haemoglobin it is but the 

 work of a few minutes perhaps as long as would be required for 

 a single carmine titration to take 50 observations from which an 

 average in the strict meaning of the term could be determined. 



In comparing the two methods there is one other point on which 

 I must touch. A few pages back I expressed admiration of the 



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+20 



FIG. 104. Curves showing Winfield's calibration of Hartridge's instrument. Ordinate = 

 percentage saturation of haemoglobin with CO. Abscissa = micrometer readings. 

 Observations from which curve was drawn. J/ = mean of 4 or 5 observations. 

 o Observations made at a later date to test whether the eye changed from time to 

 time. 



carmine method, in that it appeared to yield reliable data concerning 

 the physical laws governing the reactions of haemoglobin ; my admira- 

 tion of the spectroscopic method and my early bent filled me with 

 nothing but suspicion of spectroscopic methods in general is not 

 more qualified. It is difficult to suppose the method, were it an 

 essentially bad one, could yield the figures which Hartridge put 



100 



