46 A NEW FORM OF CLIP 



Yet spring clips are still frequently used in balsam mounting, the 

 reason being that they fulfil a twofold purpose. One use of them is 

 to produce pressure. This, as we have seen, is a bad purpose. 

 Not but what a certain small class of specimens require flattening 

 out, but this must be done before mounting them; it is too late to 

 make the attempt when they are in the balsam. Their other use is 

 to keep the cover in place while the balsam is hardening, and it is 

 for this alone that they are usually used. They do not accomplish 

 this end practically, for as a general rule, in applying the clip, the 

 cover gets slightly shifted to begin with; moreover, they are almost 

 certain to tilt the cover on one side or the other unless supports 

 have been placed round its edges. 



Nearly two years ago the idea occurred to me that what was 

 wanted was an arrangement that would hold the cover in its 

 proper position by firmly gripping the edges instead of pressing 

 down on the top of the glass. Since then I have mounted a 

 number of slides, using these " pressureless edge clips " until the 

 balsam has hardened, and with such success that now I " use no 

 other." Whilst several friends to whom I have shown the 

 *' dodge " have decided to make similar clips for their own use at 

 once, one microscopist regretted that he had not known of the 

 contrivance earlier, as he had already spoilt many slides by 

 " squashing " them. 



The figure shows one of my pressureless clips of the 

 natural size, and how they are used for keeping the cover 

 of a slide in its proper position. It will be noticed that two clips 



