894 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
pure methylated chloroform, and the containing vessel left loosely 
stoppered on the paraffin stove till all traces of alcohol have vaporized. 
Then the tissue is placed in melted paraffin, and as soon as it is warmed 
through, it is placed under an air-pump. The plate of the air-pump is 
smeared with glycerin or lard ; over this is laid a sheet of indiarubber, 
and this also treated with glycerin or lard. 
As soon as the air is exhausted from the receiver bubbles begin to 
rise, and as long as they do the pumping may be continued, though it is 
well, after a little pumping, to let the air into the receiver at least once. 
This is done by having a tap between the air inlet and the plate. The 
paraffin must be kept melted the whole time. If the paraffin solvent 
has been chloroform, the whole process takes about fifteen minutes, 
but if the preparation have been cleared with benzole and cedar oil, the 
time required is a little longer. 
The pieces of tissue dealt with are supposed to measure 1 X 1J in. 
by 1/4 in. thick. For further details and other hints the original must 
be consulted. 
Beck’s Double Slide Microtome. — This microtome introduces a new 
feature in section-cutting which Messrs. Beck consider of some import- 
ance. The single slide microtome of the usual type, when used with 
the long diagonal knife, possesses this disadvantage, that the razor 
being supported at one end only is liable to have considerable spring or 
give at its further end, thus decreasing its stability, and rendering it 
more difficult to cut the finest sections. 
The double slide microtome has a strong frame to carry the knife, 
which runs on two parallel circular bars of steel. The knife is clamped 
upon both sides of this frame, the object to be cut being between. The 
Fig. 106. Fig. 107. 
knife, which has a blade 7 in. long, is thus supported at both ends, and 
the whole extent of the blade can be used. The position of the razor 
can be varied at will ; the clamps can be placed at any position on the 
frame, so that the knife can be placed at right angles to the direction of 
cut, or in any diagonal position. 
The clamps are on a new principle. The blade of the knife rests 
upon a ledge on the lower surface of the clamp, and is held in position 
by three screws at the top, two at A (fig. 107), in front of the ledge, and 
one at B, behind the ledge ; thus by altering the relative position of these 
screws, the angle of the blade may be varied ; the under portion of the 
knife, which is flat, may be placed so as to be quite horizontal, or may 
have a slight inclination. In addition to this, these clamps are capable 
of carrying almost any razor. 
The object-holder is carried in a ball clamped in a long plate, which 
