T. CHARTERS WHITE ON MOUNTING OPAQUE OBJECTS. 233 



been accustomed in mounting any specimen as an opaque object to 

 proceed in the ordinary manner till the time arrives when the 

 covering glass is fixed, when, instead of attaching it to the cell 

 permanently, I merely lay it in its place and fix it by a minute drop 

 or two of the composition I have brought for distribution this 

 evening ; the cover is now held in close connexion with the cell, 

 and can be carried about and used with as great safety as if per- 

 manently adherent ; but with this advantage, it can be removed 

 and replaced as often as may be necessary without any difficulty, 

 and without detriment to the specimen contained in the cell. The 

 nature of the composition is exceedingly simple, being nothing 

 more than four or five parts of the ordinary yellow bees wax 

 melted with one part of Canada Balsam. 



Among the other useful purposes to which this composition may 

 be turned, I would mention one or two that may be worthy of con- 

 sideration. I find it very useful in dry mounting sucb objects as 

 the scales of Butterflies, Lepisma, or Podura, &c. We all know the 

 troubles of cement running-in in these cases, but this may be entirely 

 obviated by filling in the angle between the edge of the covering glass 

 and the glass slide with this composition, when a permanent cement 

 may be run round without any fear of a particle running in. To do 

 this neatly it is sufficient to melt a little in a spoon and paint round 

 with a warm smooth wire ; it then sets directly it touches the cold 

 glass without being drawn under by capillary attraction ; without 

 any further addition the slide is sufficiently secure to carry about — 

 it may also be used to fix the covering glass on objects recently 

 mounted in Canada balsam, but which it may be desirable to 

 remove for exhibition at a meeting. Another use to which it may 

 be put is that of fixing on the covering glass, if we are desirous of 

 watching the growth or development of an Infusorian or other 

 form of aquatic life ; by drying round the edges of the covering glass 

 and dropping a small portion of the composition here and there 

 round it, it is securely retained in its place, and may be returned to 

 the water from which the specimen was taken, and thus converting 

 the slide into a "growing" slide. It may also be employed to 

 stick glass together to make a temporary zoophyte trough ; but I 

 need not occupy the time of the meeting by any further sugges- 

 tions, for doubtless it may be put to many uses by the practical 

 minds of those present. 



