320 APPENDIX 2 



proteins of the gel nor render them insoluble in water at 37° C, and 

 the method is therefore not applicable to them; but the rate of 

 penetration of acetic acid may be tested by substituting gelatine/ 

 nucleoprotein gel (p. 315) for gelatine/albumin. 



The action of formaldehyde in rendering albumin not coagulable 



by ethanol 



Mix egg-white with twice its volume of distilled water. Clear by 

 centrifuging. Put 1-5 ml of the solution in each of two test-tubes, 

 A and B. To A add 1-5 ml of distilled w^ater, to B 1-5 ml of pure 

 (Veagent-grade') formaldehyde, 8% aqueous solution. Close the 

 tubes and turn them upside down once. Leave for 15 min. Add 

 7 ml of absolute ethanol to each. Turn each tube upside down once. 

 The fluid in tube A immediately becomes cloudy throughout, 

 while that in tube B remains clear. The next day there are visible 

 flocculi throughout the fluid in tube A, while there is only slight 

 cloudiness in tube B. 



