ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
447 
■unscrewed and the vent j\ opened ; the gas escapes through j\ as the 
liquid enters through /? r ; the cap is then firmly screwed on and 
filtering can begin. 
Fig. 111. Fig. 112. 
By means of an arm M (fig. Ill), the apparatus 
ring ; and the arm is hinged at n so that the 
removed for sterilisation and easily cleaned. The 
arm forms part of a hollow tripod stand, and can 
be raised up and down in a tube K ; it can also 
be rotated, and clamped in any desired position by 
the screw 7 r 
In order to sterilise small quantities of liquids, 
the bougie can be jacketed in a glass tube (fig. 113) 
of suitable diameter. A caoutchouc band J x is 
passed round jacket and bougie, and the whole 
placed in the filter. This application is very advan- 
tageous. 
Fig. 112 shows a cross-section of E surrounded 
by the ring F, and of the caoutchouc tube c pene- 
trating through the opening e 1 of F. 
For the filtration of a litre of blood-serum 5 to 
10 minutes suffices, and ihe end of the process is in- 
dicated by the passing of the acid through the bougie 
and the frotliing-up of the liquid in the flask C. 
The cock i 2 is then shut off and^ opened ; the pres- 
sure being thus released and the process completed. 
The tube c is closed by a pinch-cock and, together 
with the flask C, removed. 
If it should be desired to filter also the liquid 
remaining in the filter, the apparatus is inverted so 
that the liquid runs into the large upper part, the 
bougie is lemoved and the jacket tube J inserted; 
the apparatus is thus restored to its first position, 
whereby the liquid enters J, and the filtering goes 
on as before. 
By the arrangement shown in fig. 114, such 
liquids as agar-agar, Ac., can be fitered. In this 
case a metal-piece Q replaces the bougie. Q is 
perforated and can be covered by fine muslin and 
several layers of filter paper, any free space being 
wool, pressed down by a well-fitt : ng cap S. T is 
is held in a clamp- 
apparatus may ^be 
Fig. 113. 
Fig. 111. 
filled with asbestos 
a funnel, and Y a 
