730 APPENDIX I 



sufficient pressure. Two pennies suffice for most purposes. This 

 method avoids the messiness often associated with the use of 

 spring, clips, and the pressure can be much more accurately 

 adjusted to requirements. 



1429. How to Remove Coverslips. It is often desirable to 

 remove the coverslip from an old preparation in order to restain 

 the sections or to replace a cracked cover. The safest plan is to 

 place such a slide in a jar of xylol and put it aside until the cover 

 loosens. Sometimes the addition of a little absolute alcohol to 

 the xylol helps to dissolve away the damar or balsam. Carlson 

 {Science, Ixxxi, 1935, p. 365) recommends a mixture of 9 parts 

 xylol and 1 part of n-butyl alcohol, since it works much more 

 rapidly than xylol alone. Caution — ^w-butyl alcohol will dissolve 

 anilin dyes and should not be used if this matters. 



The quickest method of removing coverslips is to warm the 

 slide cautiously over a small flame and pull the cover off with the 

 fingers ! If done skilfully, few, if any, of the the sections will be 

 disturbed, but the method is not recommended for valuable slides. 



1429 his. Tap Water, Tap Water Substitute, Alkaline Water. 

 Some tap waters are alkaline enough to "blue" hsematoxylin, 

 and to wash traces of acid out of stained sections and smears. 

 Others are not suitable, and in that case you keep a tap water 

 substitute, which is merely distilled, or more or less neutral tap 

 water with 0-2% to 0-5% sodium bicarbonate added. This is 

 washed off with distilled water. S. G. Scott's tap water sub- 

 stitute is KHCO3, 2 gm., MgS04, 20 gm,, Aq, dest. 1,000 cc, 

 with a crystal of thymol to prevent growth of moulds. Tap 

 water substitute is not intended for washing out after fixations. 

 It would be unsuitable for this purpose. 



