108 Master Minds of Modern Scie?ice 



On one occasion Mr Haldane wanted to know what 

 happened to a man when he became very acid or 

 very alkaline. Many of us know by unpleasant experi- 

 ence what it is to be too acid. The acid stored by the 

 digestive organs is hydrochloric, and anyone who gets 

 too acid suffers from that peculiarly distressing form of 

 indigestion known as heartburn. This actually has 

 nothing to do with the heart, but the sensation is very 

 disagreeable, and the commonest and most obvious 

 remedy is an alkaline substance such as bicarbonate of 

 soda. 



Mr Haldane and one of his colleagues made themselves 

 alkaline by over-breathing and by eating up to three 

 ounces of bicarbonate of soda. The use of bicarbonate 

 for this purpose is obvious enough, but the resource of 

 over-breathing is less so. We all know that the lungs 

 supply the body with oxygen, and remove the carbonic 

 acid which is formed by the process of digestion. If you 

 over-breathe you get rid of too much carbonic acid, which 

 is the factor regulating your rate of breathing. You blow 

 it all out, and the results are curious and unpleasant. 

 You get ' pins and needles ' in your hands, feet, and face, 

 and if you persist the hands become stiff and the wrists 

 bend. On one occasion, after an experiment in over- 

 breathing, Mr Haldane suffered for no less than an 

 hour and a half from spasms of hands and face. When 

 conducting an experiment of this kind the experimenter's 

 chief trouble is that he is very apt to fall sound asleep, and 

 so he requires a helper to prod him into wakefulness 

 again. 



These experiments threw much light on a disease called 

 tetany (not tetanus, which is quite different and much 

 more dangerous), of which the symptoms are cramp of the 

 hands, feet, face, and sometimes of the windpipe. 



So much for making oneself alkaline ; achieving great 

 acidity was a much more difficult and dangerous matter. 



