10G 
Journal of the 
On Cleaning Used Slides and Covers . 
By F. Barnard. 
[Bead 24tli February, 1881.] 
I think many members may be surprised at my reading a paper 
upon such a subject as the above, but as we have many among 
us who are young beginners, I think I may be excused. 
'W e have all made unsatisfactory slides. Some perhaps have 
been put into our collections because of the trouble it takes to clean 
the slides and covers. Also, we often have slides smeared with 
Canada balsam in our failures to mount. 
In an English periodical I have seen the question asked more 
than once, “ How to clean old slides.” One answer particularly 
struck me — “to heat the slides in sulphuric acid;” another, rather 
more comfortable to the fingers —“ to boil them in a pipkin with 
a little soap three hours,” and if that did not remove the balsam 
to repeat the operation. Another says there is nothing like 
benzine; and I believe every one has a plan of his own which 
makes it rather puzzling to offer another way. 
My plan of proceeding is this : To warm the slide over a spirit 
lamp and remove the cover, which I at once drop into a bottle 
containing methylated spirit of wine, to which has been added 25 
per cent, of liquor potassse. I then scrape off what balsam I can 
with an old knife, and with a rag wetted with the above mixture 
clean the slide. Afterwards, a second rag wetted with the same 
liquid is used if necessary ; then, while wet , the slides are dropped 
into a basin of water; it will then only be necessary to thoroughly 
wipe them with a clean cloth. Breathing on them will show at 
once whether they are clean or not. 
During the time I have been cleaning the slides the cover 
glasses have been soaking in spirit and potash. They may now be 
removed one by one and wiped on a rag. If necessary they can 
be so treated a second time; but in either case they are to be 
dropped while wet into clean water. 
In removing the covers it will be found that the spirit and 
potash has decomposed the balsam and any gold size, black varnish, 
etc., upon them, and the dropping them while wet into the water 
prevents the adherence of any particles by the decomposition 
caused by it. 
