53 
The little bulbs in which the serum is preserved, shown in tig. S, 
are made of amber glass. The following method is used in filling and 
C* C 
sealing these bulbs: 
Cotton is first introduced in the neck as far as the constriction. 
Then about 1 gram of phosphoric anhydrid is placed in one of the 
bulbs. The neck through which the acid has entered the little 
apparatus is now sealed ofl' by the blowpipe. Then about 1.'2 grams 
of the dried serum are placed in the other bulb. The neck, from the 
serum side, is connected with a vacuum apparatus, and as soon as the 
vacuum is sufficiently high this is also hermetically sealed. 
Each bulb is now sealed in a black box, which excludes the light, 
and is kept in the ice box at 5° C.. as liefore stated. 
From this arrangement it will be seen that the powdered serum is 
kept dry. free from contact with the oxygen of the air, guarded 
against the action of light, and preserved at a constant low tempera- 
ture. 
cotTon 
Fig. 8 . — U-shaped tubes used for preserving the standard serum. Exact size. 
