Appendix to Lecture of Jan. 22, 1915 X'2r> 



diffusing at atmospheric pressure. The tension of the alcohol being 

 about 32 mm., the proportional rate at TOO mm. would be 570 mgms., 

 or 275 c.c. of N.T.P. vapour, per sq. cm. per day. This is some 

 1-1:5 times the volume rate found for air at 15' C. on the same 

 memljrane. 



Traxsmissiox THROuriH Rubber of (tases Dissolved ix 



THE biMERSIXG LIQUIDS. 



The rate of diffusion through the indiarubber of gases dissolved 

 in various liquids was investigated along with the above measure- 

 ments of liquid vapour transmission. A^arious gases were dissolved 

 in the water, alcohol, etc., in which the membrane was immersed. 

 The increase of gas pressure was measured in the exhausted McLeod 

 gauge to which the membrane and condensing U-tube were con- 

 nected, and thereby the amount of diffusion of the dissolved gases 

 through the membrane is revealed. Instead of a gas rate of the 

 order of 2 c.c. per day per sq. cm. obtained with the membrane 

 exposed in air, the following values were obtained : — 



I. — Water and Aqueous Solutions round Membrane. 



c.c. per dav per sq. cm. 



Freshly boiled out, distilled water • 09 to • 04 



Air saturated distilled water 0-414 



Hydrogen saturated distilled water 1*62 



Carbonic acid saturated distilled water ... 15 -5 



Cane sugar solution, 30 per cent. Freshly boiled ... 0"017 

 36 „ ., 0-011 to 0-006 

 „ „ 36 „ Exposed to air 2 days 0-09 

 Gum acacia solution, S.G. 1-07. Freshly boiled ... 0-010 

 Calcium chloride, 60 per cent solution. Freshly boiled 0*007 

 Hydrochloric acid solution, I Not boiled ; 1 0-19, falling 

 3 per cent < metal protected > to 0*06 



Acetic acid solution, 3 ,, j by rubber ) ... 0*90 

 Formic ,, 3 „ 0-45 



II. — Alcohol. 



Freshly boiled under exhaust • 4 to - 6 



Air saturated ... 1 • 26 



Hydrogen saturated ... ... ... ... 3-5 



Carbonic acid saturated .-. 25*0 



1 per cent alcohol in water, boiled ... ... ... 0-05 



5 „ „ „ „ 0-11 



10 „ „ „ „ 0-27 



III. — Glycerin. 



Immersed in 96 per cent glycerin • 0084 



,, 50 ,, ,, (freshlv boiled water 



used) 0-027 



,, 50 ,, ,, air saturated 0-09 



It would thus appear that the relative rates of gases in solution 

 is not so low as their proportional lowering of volume concentration 



