538 



Proceedings of the Royal Physical Society. 



wadding (care having been taken to preserve the inner 

 surface, by folding it inwards). There is no necessity to 

 sterilise after this has been once done, all that is necessary 

 subsequently is to heat sufficiently to render the gelatine 

 fluid. This apparatus is specially useful for milk, as the 

 cream always rises to the surface and is so left to the last. 

 Another new piece of apparatus (Fig. 18) is one which I 



Fig. 18. 



(a) Air jar; {h) perforated india-rubber; (c, c) elbow tubes; {d) exhaust 

 tube ; (e) litre flask with (/) tube leading from it. 



think may take the place of the Hesse's tube. It consists 

 of a chamber {ct) almost like one of the potato chambers, 

 but in one piece, with an aperture at the top, over which 

 is tied a piece of india-rubber sheeting (h) with a minute 

 perforation. At the level of a quarter of an inch from 

 the bottom of the jar, two small glass tubes, each with an 

 elbow (c, c), are let into the glass, opposite one another. 

 From each of these runs a piece of india-rubber tubing- 

 going to join a T tube (d), which in turn is attached to 

 an exhaust apparatus. By means of this piece of apparatus 



