The Microscope. 81 



In reference to its employment as a foundation ring, Mr. Fr. 

 Dienelt says:* It answers much better than shellac in mounting 

 insects, whole or in parts, or than other materials where a thick 

 layer of balsam is needed. Much trouble is caused in finishing 

 with alcoholic cements, because the alcohol softens the thin crust 

 of hardened balsam at the edge of the cover, and air bubbles ap- 

 pear. The same often happens again when finishing with colored 

 cements. With glycerine mounts, that is, when glycerine is used 

 as the preservative medium to surround the object beneath the 

 thin cover, then the finishing cement may be Brown's rubber so- 

 lution; and in similar instances shellac may be used to fasten the 

 cover in place over a cell of some other cement, but as a rule 

 it seems to me best to use the same cement for both purposes. 

 In this way all danger of chemical action between the two is 

 avoided. If ornate slides are desired they may be made by 

 adding stripes around the cover with shellac colored with any of 

 the aniline dyes, or with the beautifully colored cements pre- 

 pared by the Rev. J. D. King, of Cottage City, Mass. But, 

 again it seems to me preferable to avoid the use of these colored 

 applications, unless it can be done with skill, as otherwise the 

 result is likely to be tawdry. 



Gold size has the advantage of possessing little or no affinity 

 for Canada balsam, unless the latter is used unprepared by the 

 microscopist or by the dealers, that is, unless it is used as in the 

 condition in which it is when bought at the druggist's, a method 

 that is almost never employed at the present time. Another ex- 

 ception is when the balsam is thinned with turpentine, but this 

 is another thing that is seldom done. The balsam is almost 

 always put through certain processes, as we shall learn hereafter^ 

 and then dissolved in benzol, chloroform, or in some other men- 

 strum that evaporates rapidly. The reader need have no fear 

 that his thinned gold size will run under the cover unless he uses, 

 as he should not, the ordinary Canada balsam to be had from 

 the druggist. All this will be referred to again, at the risk of 

 repetition. 



Gold size may be used to fasten the cover in place over a bal- 

 sam mount, and this is a great advantage, as every balsam mount 

 should be protected by something of the kind, although the hard- 

 ened resin will for a long time hold the cover in position; it will 



The Miceoscope, September, 1890, p. 281. 

 6 



