NATURAL HISTORY SOCIETY OF GLASGOW. 5 



objects dry, this method does admirably, but it is not sufficient for 

 small dissections which require to be clearly defined, and are besides 

 apt to be obscured by the gum. The next development of the 

 cardboard method was the employment of balsam, and that the 

 latter preserving medium can be used with success, will, I think, be 

 admitted by every one who examines the objects I exhibit in illus- 

 tration of my remarks. 



I will now proceed to describe the process. In the first place, 

 very fine cardboard must be obtained, and cut into pieces, say 9 lines 

 by 6. A hole 2£ to 3 lines across is punched at one end in the 

 centre, and a line and a half to 2 lines from the edge. Next a cover 

 glass is cleaned, and is fastened to the lower side of the card by 

 means of balsam, so as to cover the hole, care being taken to use 

 plenty of it. These two processes — the punching of the holes and 

 the fastening of the cover glass — are best done wholesale, so that 

 the prepared cards may be always at hand when wanted. Supposing 

 then that the object to be examined is ready to be mounted, the 

 next procedure is to fill up the cell in the card with balsam, to near 

 the top, say within a fourth of the top. The balsam is then made 

 as level as possible, and the object or objects arranged on it. Place 

 this aside in some place where no dust can get near for a day or 

 two, and then finish the business by filling up the cell with balsam 

 till it overflows, and pressing a cover glass over it. Next place in 

 a flat position for two or three days, when all superfluous balsam 

 may be removed, the glasses cleaned, the nature of the object 

 noted, by means of a crowquill, on the lower end of the card) 

 and lastly, a pin being stuck through it when it is ready for the 

 cabinet. I should explain that the object of not putting the top 

 glass on at once, but leaving the objects to harden in the balsam 

 for a time, is, that in this way they are not apt to be shifted out of 

 position when the top glass is applied, or in the endeavours to get 

 rid of large air bubbles. In the same way the reason of leaving the 

 cards flat for two or three days is to allow the balsam to harden, as 

 the objects flow down if the card is allowed to hang horizontally 

 before this takes place. One thing, however, is necessary for success, 

 and that is, that properly prepared balsam be used. This is done 

 by dissolving Canada balsam in benzine till it becomes of the 

 consistency of cream. With this there is no trouble with air bubbles, 

 in fact it is scarcely necessary to drive them out, as the bubbles 

 disappear of themselves in a day or two. 



