THE NATURE OF HEMOGLOBIN SOLUTION 83 



are so interwoven that it is not possible to consider each one quite 

 separately from the other two. Nevertheless we may first say some- 

 thing about the effect of salts. Salts have a wonderful effect in 

 stabilising the osmotic pressure. Any dUute solution of haemoglobin 

 which contains more than the merest trace of salts (about -01 

 molecular), of whatever hydrogen-ion concentration, has an osmotic 

 pressure of about 2-6 mm. Hg for each per cent.^ of haemoglobin 

 present. When one gets to solutions so free from salts as to have a 

 less saline content than '01 molecular the osmotic pressure rapidly 

 rises (12). 



It follows therefore that if the effect of varying the hydrogen-ion 

 concentration is to be brought about the solution must be salt free. 

 Fig. 17 shows that in a salt-free solution the osmotic pressure is 2-6 

 for each per cent, of haemoglobin at the isoelectric point, but that 

 on either side of neutraUty the pressure rises rapidly — on the alkaline 

 side owing to the formation of sodium haemoglobinate, on the acid 

 side owing to the formation of haemoglobin chloride (9). 



The above statements apply to solutions of less haemoglobin con- 

 centration than about 4 per cent. Above this strength the osmotic 

 pressure for each per cent, of haemoglobin rises. At concentrations 

 such as are found in the red blood corpuscle, 30-40 per cent., the 

 osmotic pressure is much higher relatively, being about 5 mm. or 

 even more for each per cent. (i2) 



REFERENCES 



(1) Algernon Blackwood. Episodes before Thirty. London, 1923. 



(2) Bayliss. Principles oj General Physiology, xxi. 615. 1924. 



(3) Barcroft and Roberts. Journ. Physiol, xxxix. 143. 1909. 



(4) Hill, A. V. Journ. Physiol. XL. iv (Proceedings). 1910. 

 Biochem. Journ. vii. 471. 1913. 



(5) HiJFNER AND Gansser. Arch. f. Anat. u. Physiol, p. 209. 1907. 



(6) Reid. Journ. Physiol, xxxiii. 12. 1905. 



(7) RoAF. Journ. Physiol, xxxvni. i (Proceedings). 1909. 



(8) Adair. Proc. Roy. Soc. A. cviii. 627. 1925. 



(9) Adair. Proc. Roy. Soc. A. cix. 292. 1925. 



(10) Schafer. Text Book of Physiology, I. 23'i. 1898. 



(11) Stoddard and Adair. Journ. Biol. Chem. lvii. 437. 1923. 



(12) Barcroft. Journ. Chem. Soc. -p. 114:6. May, 1926. 



^ The strength of the solution may be measured without drying the haemoglobin 

 ■either spectrophotometrically(iO) or refractometrically(ii). 



6-2 



