42 



discussed by Professor W. M. Bayliss in the Second Report of Colloidal 

 Chemistry, 1918, p. 151. The study of colloidal chemistry has thrown 

 new light upon the problem of the abnormal solubility of these gases 

 in blood. Findlay and Harbyi* (1908) suggested that the effect 

 is due, partly to absorption on the surface of the disperse phase, and 

 partly to ordinary chemical combination. The accepted view was 

 that absorption of oxygen by blood was due to the formation of a 

 compound of oxygen mth the haemoglobin ; and this view has recently 

 received the support of Barcroft*. According to Peters** — on the 

 basis of the iron content of haemoglobin — one molecule of haemoglobin 

 combines with one molecule of oxygen, but the total quantity of 

 oxygen absorbed, for one gram of iron, varies according to the nature 

 of the blood, being 280 c.c. to 401 c.c. for pig's blood and 320 c.c. to 

 468 c.c. for dog's blood. This considerable variation must be due 

 to the difference in the chemical or physical nature of the haemoglobin 

 and not to any great extent to variation in the plasma, for the total 

 amount absorbed by centiifuged plasma of dog's blood is only 

 12-6 c.c, whereas the variation in total gas absorbed is 40 c.c. to 

 70 c.c. In order to investigate the influence of colloidal haemoglobin 

 on the solubihty, Findlayi^--^ and co-workers carried out a series 

 of systematic investigations on the influence of coUoids and fine 

 suspensions on the gas solubility. The specific effect due to the 

 colloid was investigated by studying the influence of concentration 

 and pressure on the solubihty coefficient. The following are tj-pical 

 of the 17 coUoids used : — ferric hydroxide, gelatin, starch, ox blood, 

 haemoglobin, peptone. Carbon-dioxide and nitrous oxide were used, 

 and it ^^•as found that, for both gases, at pressures below atmospheric, 

 the solubUity (A) is sometimes less, sometimes more, than in water, 

 it always faUs with increasing pressure, and passing through a 

 minimum, rises again shghtly. 



The pressure at which the minimum occurs is practically constant 

 for aU concentrations of a particular sol, but varies for different 

 solutions. It has been tentatively suggested by Findlay and Creighton^"* 

 that this unique behaviour is due to gas solubihty in the disperse 

 ohase and since the solubility then no longer follows Hemy's Law, it 

 •nust be assumed that gas polymerises in this phase. For the upward 

 trend of the curve the increased solubihty can be satisfactorily 

 interpreted in terms of the absorption law. C*2/Ci := constant 

 {e.g., serum albumen, charcoal, suspensions). 



It is well known that the solubihty of gases in salt solutions decreases 

 with increasing salt concentration-* — provided there is no chemical 

 reaction. About 20 aqueous solutions of non-electrolytes have been 

 studied, and in three only, Quinol, ResorcinoP", and Anfline^^ is the 

 solubihty of carbon-dioxide greater than in water. These exceptions 

 are no doubt due to chemical combination of the solute -nith the gas. 



In considering the influence of the concentration of colloids on 

 solubility, distinction must be drawn between suspensoids and 

 emulsoids. In physiological and technical chemistry, suspensoids 

 occur but seldom. Geffcken^* and Findlay^^ have both found that 

 the solubility (A) of carbon-dioxide in aisenious sulphide sols, is less 

 than in water, and the latter has observed that it is constant for 



