THE MICROSCOPE. 37 
CARMINE STAINING.—Obersteiner suggests heating the stain- 
ing fluid containing the specimens. Specimens hardened for any 
length of time take coloring matter up so slowly that many days 
elapse before the process is complete. By subjecting the staining 
fluid containing the sections to a water-bath heated by a spirit-lamp, 
the finest staining can be accomplished in from one to two hours, 
and in the case of hematoxylin in even less time. The heating of 
hardened sections does not injure them in the least when the pre- 
caution is used for employing a water-bath. 
Eyre-PrecE MICROMETER.—The value of an eye-piece mi- 
crometer is comparatively slight but still it has its use. 
Mr. W. M. Bale describes a simpie method of making one 
in the Southern Science Record, an abstract of which may 
be interesting. He takes as his material fine silk ravelled 
from a ribbon. Unscrewing the field lens from an objective he 
applies two small particles of stiff balsam to the lower surface of the 
diaphragm. Then taking a small portion of the silk fibre he fixes 
one end in the balsam and then stretching the fibre fastens the other 
endin the same manner. The field lens is now replaced and the 
fibre examined and if found straight the next step follows. If not 
it is replaced by a better piece. The next step which is to attach a 
second fibre parallel to and at a given distance from the first is a 
matter of more difficulty. The distance of course will depend on 
the space to be measured. Assuming that it is to be 1-1000 of an 
inch with a C eye-piece and a ¥% inch objective it will be about a 
thirtieth of an inch, The fibre is placed in such a position and 
then the eye-piece is placed in its proper position in the microscope 
and with a 4% inch objective a stage micrometer divided to 1-1000th 
in. is examined. This will of course reveal whether the fibres of 
silk are too near or too far apart. If all right a third fibre and so 
on is attached in the same manner, and examined eachtime. If one 
of the lines is improperly placed it must of course be corrected. 
After the lines are in position Mr. Bale fixes them with slips of 
gummed paper exercising the greatest care to avoid moving the 
lines.— Scrence Record. 
