206 Chapter XIII 



practice is very great. A farmer by mere inspection will tell you the 

 weight of a bullock with an accuracy which probably exceeds that 

 claimed by Haldane and Douglas for the carmine method of titra- 

 tion. 



I have never myself made a carmine titration, and had I made a 

 few I have little doubt that I should have failed to obtain concordant 

 results : but such a failure would have formed no just criticism of the 

 work of those accomplished in the method and would therefore have 

 been a mere waste of my own time. 



Anyone who reads the recent work of Haldane and Douglas must 

 be struck by the way in which the method has served them in the 

 determination of the physical relation of oxygen and carbon monoxide 

 to shed blood. Take for instance the curves given in Fig. 35 and 

 these are a sample of many determined since they are mathemati- 

 cally fair curves with equations, and not only so, but there is inde- 

 pendent reason to believe that they are not only fair curves, but that 

 the properties of haemoglobin are such that they could not be of any 

 other shapes than the ones shown. Such curves do not result from 

 unsound experiments. 



In spite of the last consideration enough has been said to form 

 a sufficient apology if apology were necessary for Hartridge to 

 take the ground that an independent* method of determining the 

 CO haemoglobin present in blood was a desirable preliminary to an 

 independent examination of Haldane's results. 



Apology is not necessary however. It is of the essence of sound 

 experiment that the experimental methods should be varied in every 

 possible way. This, at all events, is the school in which I have been 

 brought up. It is the school in which my foretime lecturer, now my 

 friend and colleague Mr C. T. Heycock, F.R.S., untiringly pointed the 

 moral from the work of Stas on the atomic weight of silver. 



I should never concede on the one hand that a blood gas worker 

 in the Cambridge laboratory owed an apology to his predecessors for 



* Hartridge commenced in 1909 with the idea of revising the method as used by 

 Haldane and Lorrain Smith. Between the summer of that year and the spring of the 

 following, my results on salts, temperature, &c. were published. They materially 

 altered the problem for him and also caused the work to be taken up again by Haldane 

 and Douglas who published their work to some extent as they went. Apart from this 

 I believe neither they nor Hartridge were cognisant of the work of the other until 

 a short time before their final publication. The findings of the two sets of observers, 

 which agree very closely in so far as the physical properties of haemoglobin are con- 

 cerned, have therefore the merit of being independent. 



