Tue Microscopr. QA5 
absolute alchohol.* It will not be possible to dissolve all the 
lac, and after standing afew days the supernatant fluid should 
be decanted and the sediment thrown away. In my early days 
with lac I found great difficulty in getting a clear, transparent 
coating on the slide and was about ready to discard the process 
in disgust, but I found that on heating the slide to say about 
150° F. the coating could be applied with perfect success every 
time. It should be applied with a glass rod the same as collo- 
dion. 
Creosote is not used as extensively as a clearing medium as 
it deserves to be. It has one excellent advantage which is lack- 
ing in clove oil and that is that it will dissolve a certain pro- 
portion of water. Hence it is possible to clear a slide without 
the use of absolute alcohol. The steps are the same as with oil 
of clove. The only objection which I have found with its use is 
its disagreeable smell. It mixes perfectly with balsam. 
One of the bits of technique which has given me the most 
satisfaction is the recent one of overstaining and then with- 
drawing most of the color. It is just splendid fornuclei. After 
the sections are fastened to the slide and the paraffin is dis- 
solved away by turpentine, I place it in a bottle of alcohol to 
remove the turpentine. It is then ready for staining. It is 
placed in a bottle of the desired stain and allowed to remain for 
a considerale time, far longer than is usually the case. After 
the lapse of from half an hour with hematoxylin to two or three 
days with some of the carmines, the slide is ready for the next 
operation. It is now overstained. The problem is to dispose 
of some of the superfluous color. This is accomplished by 
placing it in a bottle of aleohol acidulated with a few drops of 
hydrochloric acid, say about ten to the pint. Here it remains 
until the sections are appreciably light, and is then washed with 
pure alcohol and is then mounted in the usual manner. 
In keeping my section knives when not in use I have 
adopted a very simple expedient. I make a longitudinal deep 
saw scarf in a block of wood and in this the edge of the knife is 
* A contemporary recently said that when microscopists say ‘‘ absolute alco- 
hol” they mean ninety-five per cent. spirit. With all due deference to the author 
quoted we should say that they mean nothing of the kind, and in most microscop- 
ical operations ninety-five per,cent. alcohol will not do in the place of absolute. 
