14 SOME HINTS ON THE PREPARATION AND 



taken to -allow each coat to harden before applying a fresh one, 

 which is rapidly accomplished with this invaluable cement. A nar- 

 row ring of some bright color makes a pleasing finish, and can be 

 readily made by adding to the ordinary damar medium a sufficient 

 quantity of any desired color, ground in a little oil. All these ce- 

 ments should be applied by small red sable brushes, and the best 

 mode of using them is to have the bottles in which they are con- 

 tained, filled with long, tapering corks, into the under side of which 

 the brushes are to be fastened. They are thus always immersed in 

 the cement when not in use, and never can become stiff and dry; 

 whilst they undergo no apparent deterioration. I am now using in 

 my white zinc bottle the same brush that I placed there six years ago, 

 during which time it has been employed to ring many thousands of 

 slides, and is now as " good as new." The long cork forms a very 

 convenient handle for the brush, and if care be taken to wipe it and 

 the neck of the bottle with alcohol, occasionally, they will never 

 stick together. 



It is to be noted that the flattening between glass slips, etc., is 

 only necessary in the case of objects of considerable thickness, such 

 as the fly's leg we have been preparing. All thin objects, as 

 sections of animal or vegetable tissues, etc., may be carried through 

 the alcohol and subsequent stages, in the same manner as that pur- 

 sued with the fly's wing; or, if perfectly dry, may be at once im- 

 mersed in the oil of cloves, or even mounted in the balsam, without 

 previous soaking in anything. 



And now, having brought our balsam mounts to a successful 

 completion, I must also make an ending of the present paper. In 

 future ones (if this be well received), I propose to give some practi- 

 cal hints on mounting in the dry way, both opaque and transparent 

 objects suited to that method of preparation; also on fluid mounts 

 of various sorts, and possibly others on the double staining of 

 vegetable tissues. 



Should any of my readers desire to see a balsam mount pre- 

 pared according to the foregoing directions, I shall be pleased to 

 exchange with him or her for any well prepared original slide. 



