1893.] MICROSCOPICAL JOURNAL. 337 



this is the case, you can never j;et a solution to spread properly 

 over the slide as though it were greasy. The only thing is to 

 use the other side, if clean enough, or if hoth sides are bad, the 

 glass can serve for any ordinary slide, the si)ot only being seen 

 when breathed upon. If the spoilt preparation was mounted 

 in balsam or any other medium, the slide should be warmed 

 on the hot plate, until the cover can be slipped off ])y the knife. 

 Then scrape off all the balsam you can, and clean the rest off 

 with methyl alcohol, putting the glasses as before under water. 



If the slides have had a ring made with asphalt or any other 

 varnish, it will be necessary to carefully scrape it all off with a 

 knife. Heat will not soften it. 



The covers can be dropped into a bottle containing methyl 

 alcohol for cleaning at leisure. 



When you have a batch of glasses ready for washing, put 

 them in a pretty strong solution of washing soda, leaving them 

 in it about twenty-four hours, thoroughly rinse in clean water, 

 rubbing the glasses well with the thumb, changing the water 

 occasionally. When sufficiently rinsed rub dry with a clean 

 cloth, using the first one to dry and another to polish. The 

 slides, when put away, should be wrapped up in soft paper to 

 keep them clean. When quite dry, breath on them to see that 

 they are thoroughly cleaned. Those slides not sufficiently clean 

 should be put at one side for another treatment with soda, it 

 frequently happening that they have not been properly sub- 

 jected to the action of the soda from lying closely one on the 

 other. 



Those glasses that are clean should be wrapped up in soft pa- 

 per to make a packet from which you can always be sure of 

 getting a slide fit for use. 



III. — TARTRATE OF SODA. 



To prepare slides of tartrate of soda, it is necessary to make 

 the solution yourself. I have found, on attempting to use 

 the crystals of tartrate of soda as jjurchased, that they yield 

 a different and very insignificant form. Make a strong solut- 

 tion of tartaric acid and carefully neutralize with carbonate of 

 soda. When the solution becomes solid add a little distilled 

 water to dissolve the j^recipitate, allow to settle, when it will 

 be ready for service. Now, I usually with all the solutions al- 



