Monthly Microscopical"! 
Journal, Aug. 1, 1869. J 
Microscojpical Besearch. 
89 
Kecklinghausen has introduced tlie use of moist chambers. 
The fundamental idea for such an arrangement was that the object 
be introduced into a space, saturated with aqueous vapour, and this 
appeared especially necessary when it became desirable to examine 
without the glass cover. In such a case the object is partially 
surrounded by an atmosphere, to which it gives off aqueous vapour 
should the atmosphere not be saturated with such vapour already. 
If we, on the other hand, take into consideration that the 
deposition of aqueous vapours from a saturated atmosphere upon 
such an object is dependent on the temperature of the latter, it will 
be easily understood how difficult it is to arrange everything in 
such a way that water is neither taken up nor given off. At any 
rate the errors will diminish with the dimensions of the atmosphere 
which surrounds the object. The atmosphere should therefore be 
made as small as possible, and should as much as possible be 
reduced to nil, therefore as long as possible one should work with 
a glass cover the margins of which are oiled. The pressure which 
it exerts upon the object is inconsiderable, while it can easily be 
avoided. It is only necessary to make a wall of oil, to apply the 
drop within this wall, and then to cover it, in order to be protected 
against the pressure exerted by the glass cover. But as regards 
the experiment, it may from other causes become necessary to 
surround the preparation with an atmosphere. The influence of 
various gases, for example, may have to be passed over it in the 
course of the experiment. In such a case an actual chamber must 
be established, and this must be kept as small as possible as long 
as no other arrangements are made to regulate the movements of 
the aqueous vapour. For this purpose I would propose to apply 
upon the ordinary slide a ring of putty of the required thickness, to 
place the object, as is now practised everywhere, upon the glass 
cover, to bring this down upon the wall of the putty with the 
object turned downwards, and to press it down gently by running 
the handle of the scalpel over it. A drop of water upon the bottom 
of the slide will suffice to saturate the space with aqueous vapour, 
and to preserve the object from drying. But here also great 
caution should be used, for it will be found that the dry and 
pohshed cover-plate is tarnished as soon as it is put upon the wall 
of putty. The drop of fluid must therefore have a small surface, 
in order not to evaporate too much ; it must, on the other hand, 
not be too small, lest the object dry too soon. 
Such a chamber may easily be transformed into a so-called gas 
chamber. Into either side of the soft waU of putty, corresponding 
to the middle line of the glass slide, a small glass tube may be 
introduced, to each of which is attached a correspondingly diminu- 
tive caoutchouc tube. When no gas is to be sent through them, 
they are closed by small pinch-cocks. When the gas is to be passed 
