ON MOUNTING OBJECTS. 105 



finger and thumb, and held as represented in the woodcut, 

 when the wheel is put in motion, and a perfect circle is 

 rapidly formed ; the cell is then removed and put aside to 

 dry. In the same way, by securing a sheet of thin glass 

 under the brass springs, and substituting for the pencil 

 a cutting diamond, a circular cover may be readily cut 

 out. A cutting diamond is not only useful to the micro- 

 scopist for the above purpose, but also for writing the 

 names of mounted objects on the ends of the glass slides. 

 A glazier's diamond for cutting glass slides is both conve- 

 nient and economical : the mode of using it may be acquired 

 in any glazier's shop. Mr. Brooke used a small brass press 

 for the purpose of cutting out thin glass for cells. This 

 does its work so quickly and so well, that it is likely to 

 supersede all other methods. 



On mounting and preserving Objects. Microscopic ob- 

 jects are usually mounted on slips of glass three inches by 

 one inch, either dry or immersed in some fluid. The 

 minute structures, such as the tissues of animals, parts of 

 insects, vessels of plants, &c., must be preserved in thin 

 cells, made as directed above, with a small amount of 

 fluid. 1 Clean the glass with a weak solution of ammonia 

 or potash, from all grease, and wipe it dry with a piece of 

 chamois leather or cotton velvet; cloth generally leaves 

 behind it small filaments, which are always unsightly when 

 seen near the object. Let fall a drop of the preserving 

 fluid or Canada balsam on the centre of the glass ; then 

 place the object in. it with a small pair of forceps, and 



Fig. 71. 



spread it out very carefully with the point of one of your 

 fine needles. Select a thin glass cover, previously cleaned, 



(1) Cells for microscopic purposes may be purchased of Mr. Bender, 6 Bruns- 

 wick Place, City Road, or of Mr. Baker, 244, High Holborn. 



