ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 695 
Obtaining Germ-free Water with Calcium Chloride.* — Germ-free 
water, says Herr Bassenge, can be obtained in less than 15 minutes by 
chemical means. In order to render water which is most impure from the 
presence of pathogenic bacteria perfectly germ-free, it is sufficient to add 
0*0978 grm. of pure calcium chloride (equivalent to about O’ 15 grm. 
of commercial chloride) to the litre, and allow it to act for 10 minutes. 
The quantity of chloride may be decreased if its action be prolonged, e. g. 
Tvo hours requires only 0*0108 grm. The chloride not used in the 
disinfection or in the form of hypochlorous acid is reduced by the 
addition of bisulphite of calcium, a precipitate of sulphate of lime being 
deposited. Water thus treated is harmless, has no ill flavour, and is 
of increased hardness. It can be used for a long time without any 
influence on the organism (the author has tested it on himself), for the 
chemical treatment has only imparted to it constituents present in natural 
drinking waters. No chemical test is required to find out whether all 
excess of chloride lias been reduced ; it is quite sufficient to trust to 
taste and smell. 
Air and Germ-tight Cap for Bacteriological Work.j — Herr R. 
Burri describes an air- and bacterium-tight cap which is adapted for 
closing test-tubes or other similar 
vessels used in bacteriology. One 
of its chief merits is that it quite 
prevents diminution in bulk of the 
medium from evaporation. Fig. 
118 shows the shape and position 
of the rubber cap when placed on 
the neck of a test-tube or bottle 
before it is sterilised. At e is a 
narrow slit which leads to the under 
part of a. This slit, which can 
act like a Bunsen valve, is not 
visible externally, for its edges 
are firmly approximated. When, 
however, the contents of the vessel 
are heated and the air therein ex- 
pands, the valve opens and allows 
the gases to escape. When the pressure inside is equal to that outside 
the valve closes itself, and as the contents of the vessel cool down the 
upper part of the cap is sucked in and assumes the shape shown in 
fig. 119. In this way the vessel becomes hermetically sealed. 
Syringe for Bacteriological Purposes.^ — HerrK. Ilkewitsch uses a 
syringe for bacteriological purposes, which consists of a graduated glass 
pipette a holding 1-5 and 10 ccm. At b is seen the needle fitting into 
the neck c. To the other end is joined the caoutchouc tube d , 10 cm. long, 
which runs into the rubber ball e with a diameter of about 5 cm. From 
the side of the ball projects a short tube made of hard rubber and 
containing a valve so arranged that it is closed when the ball is pressed 
* Zeitschr. f. Hygiene u. Infektionskrank., xx. p. 227. See Centralbl. f. Bak- 
teriol. u. Parasitenk., l t0 Abt., xviii. (1895) pp. 239-40. 
f Centralbl. f. Bakteriol. u. Parasitenk., 2 te Abt., i. (1895) pp. 627-9 (2 figs.). 
j Op. cit., l te Abt., xviii. (1895) pp. 55-9 (3 figs.). 
Fig. 119. 
