652 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
immersed in the water-bath, and as the bar lengthens from the increased 
temperature, its upper end presses directly against a caoutchouc tube, 
through which the gas passes to the flame. Hence the flame diminishes 
and consequently the temperature of the thermostat. In the second 
model the end of the zinc bar is bevelled and its edge made to press 
against a lever, which is always kept opposed to the bar by means of a 
spring. The other arm of the lever runs between two caoutchouc tubes, 
one of which introduces a cooling, the other a heating medium. 
The author states that having used these for some years he is able 
to testify that they work with great efficiency and accuracy, and gives a 
table recording their diurnal variations, which are certainly small. For 
the minute details of construction the original must be consulted. 
The question of heating media is then discussed and an ingenious 
method for employing alcohol is described. In this case the alcohol is 
supplied to the flame through a tube coming from a reservoir fitted with a 
Marriotte’s tube. The tube has an overflow pipe placed at an angle between 
the flame and the regulator. The regulator placed within the water- 
bath embraces the caoutchouc tube as it passes from the spirit reservoir 
to the flame, and so acts that as the bar expands it nips the tube, and 
thus diminishes the flow to the lamp. 
Thermoregulator for large Drying-stoves and Incubators.* — 
M. Roux recommends the thermoregulator which has been in use at the 
Pasteur Institute for some years, as being very suitable for large ovens 
or incubators. 
It is made of two metal bars welded together and bent to a U-shape. 
The inner bar is made of steel and the outer one of zinc. These are 
massive enough to prevent any springing. The length of the legs of the 
U are from thirty to forty cm. 
The variations in temperature as recorded from the use of the large 
incubator at the Institute are said never to exceed 0 • 5°. 
Capillary-siphon-dropping Bottle, t — Prof. M. W. Beyerinck says 
that if the Y-shaped tube of a dropping-bottle be made of capillary size 
it will be found very useful for microscopical purposes. Thus it may 
be used for distributing small quantities, droplets, of any reagents from 
the bottle, or for capturing small animals, Infusoria, from a watch-glass, 
and so on. 
Steam-filter 4 — The apparatus devised by Dr. P. G. Unna for filtering 
agar is a hollow copper sphere, the upper half of which serves as a lid. 
In the bottom is a hole, through which passes the stem of an 
enamelled iron funnel. The top of the funnel projects above the level 
of the lower hemispherical segment or pan, and the distance between the 
edge of the funnel and the pan is about 1 cm. The pan is suspended 
on a tripod, from the ring of which a semicircular band passes over the 
pan. By means of a screw at the uppermost part of this band the lid 
is firmly screwed on. In the lid is also a small tap for letting off the 
* Annales de l’lnstitut Pasteur, 1891, p. 158. See Centralbl. f. Bakteriol. u. 
Parasitenk., ix. (1891) p. 737. 
t Centralbl. f. Bakteriol. u. Parasitenk., ix. (18S1) pp. 589-90 (1 fig.). 
% Tom. cit., pp. 749-52 (1 fig.). 
