1895 THE MICROSCOPE. 25 



object without displacing it. Then push the cover back 

 by the edge when it will take the preparation with it. 

 In this way, by a little patience, the object can be shifted 

 to any part of the slide. If you try to get it in the cen- 

 ter by pushing the cover first from the edge, you will 

 soon find that the object will work right out of the field. 

 Having got everything right and true, put a light brass 

 clip on to hold the cover in its place to dry. If you put 

 too strong a spring on the preparation it may force the 

 cover up when the spring is released. It is better to re- 

 move the surplus balsam with a knife, at once, while it 

 is soft, wiping the balsam off of the knife with a piece 

 of paper. Place the slide away for a few days to allow 

 the balsam to harden, when you can clean off the slide 

 with methylated spirit, or better with benzole. When 

 the slide is nice and clean, put it on the turn-table and 

 run a ring of gum water round the edge of the cover- 

 glass. When dry, give it another coat. This is to pre- 

 vent the white zinc or other cement being dissolved by 

 the benzole and running in under the cover-glass. If 

 pure balsam is used, there is much less risk of this oc- 

 curring. A very neat finish is given with white zinc 

 cement. It is easy to work and gives a good, hard, 

 brilliant surface, on which can be put a ring of black or 

 any other colored varnish. When you have finished, 

 clean the brush well by means of benzole ; wipe the 

 brush on a piece of paper between the fingers first, when 

 the brush can be cleaned with a very small quantity of 

 benzole and very quickly. 



The Serum Treatment of Diphtheria will be explained in 

 The Popular Science Monthly for February, by Dr. Samuel T. 

 Armstrong, Visiting Physician to the Hospital for Contagious 

 D is teases, New York. 



The article will be of much interest to bacteriologists. 



