CHAPTER VII. 



ON MOUNTING MICROSCOPIC OBJECTS. 



{I.) lYansparent or Diaphanous Objects — are usually 

 mounted on slips of glass cut of a uniform size . The dimen- 

 sions of these slides as proposed in the ' List of 2000 Mi- 

 croscopic Objects' were. No. 1 size, 3 inches long by f of 

 an inch wide ; No. 2 size, 2 inches long and f wide ; 

 No. 3, 1|^ inch long by ^ of an inch wide. The latter 

 size is seldom used except for opaque bodies, as herein- 

 after mentioned. The reason assigned by Mr. Pritchard 

 for selecting these lengths was that they are multipliers 

 of each other, and therefore the drawers or boxes con- 

 taining them can be made of uniform sizes. The Micro- 

 scopic Society of London has adopted the length of the 

 first as the standard — that is, 3 inches. This size, there- 

 fore, it will be well to retain except where economy of 

 money or sj)ace is of consequence. The No. 2 slides are 

 sometimes preferred as containing less than one-half the 

 glass and occupying a like reduced proportion of space. 

 (2.) On Cutting Glass for Slides. — The chief desiderata 

 are clearness, freedom from veins, and perfect uniformity in 

 length and breadth, whatever dimensions may be selected. 

 The latter is best effected by having a cutting-board and 



