332 



Mr. J. Bretland Farmer. On the Effect of 



similar solution of the unheated albumin, both became opalescent at a 

 temperature of 60° C, and both were completely coagulated at 62° C. 



It thus appears that, if precautions are taken to ensure appropriate 

 desiccation, it is possible to heat albumin for, at any rate, thirteen 

 hours to a temperature varying between 102 — 110° C. without producing 

 any obvious change in its ultimate molecular (or micellar 1) structure. 

 It made no difference to the result whether the heat was gradually or 

 rapidly applied. Thus, in one experiment, the temperature was raised 

 from 50° C. to 103° C. in fifteen minutes, and in other examples the 

 flask was withdrawn from the hot bath, cooled, and suddenly re- 

 immersed. How much higher the temperature could be raised without 

 producing an obvious effect, I am not prepared to say ; nor did I 

 investigate the action (if any) which might possibly be produced by a 

 much longer exposure to heat within the limits already mentioned. 

 This formed no part of my object, which was primarily to try to get a 

 point of comparison between the complex seed and the simpler but 

 still very complex proteid. 



Other experiments were made in order to test the sensitiveness of 

 the albumin to small quantities of moisture. 



For this purpose, two flasks attached to drying tubes were used, one 

 of them serving as a control experiment, and remaining unopened 

 until the end. The other was opened three times, and a small sample 

 taken out each time. By this means the ordinary air of the room 

 obtained complete access to the albumin. The duration of the experi- 

 ment was ten hours. The first sample was withdrawn after the flasks 

 had been heated to 102° C. for three hours; it dissolved and coagu- 

 lated normally. A second sample was "withdrawn after three hours 

 more, and it was found that whilst it dissolved and became opalescent 

 on heating to 60° C, the coagulation change did not at once set in, 

 but the opalescent solution became more milky and of a deeper fog- 

 yellow by transmitted light, finally coagulating at about 68° C. A 

 third sample taken out at the close of the experiment {i.e., foiu" hours 

 after the last opening of the flask) also dissolved, became sKghtly 

 opalescent at about 64° C, but did not coagulate even at 90° C, 

 although the opalescent milkiness became very pronounced. Viewed 

 by transmitted light, the solution was translucently yellow. Even 

 boiling failed to produce anything which could be fairly termed a 

 coagulum. It appeared probable that the admission of watery vapour 

 had permitted the inception of the changes which normally, at high 

 temperatures, result in coagulation ; but in this case they were 

 arrested, some precursor of alkali-albumin being probably produced, as 

 is often the case on slowly coagulating albumin solutions. Under 

 these circumstances, however, the entire mass of the albumin had 

 undergone this change. This supposition turned out to be correct, for 

 the addition of a trace of acetic acid at once caused the solution to 



