144 



THE AMERICAN MONTHLY 



[August, 



thoroughly cleaned from the slide 

 and cover, the preparation is placed 

 on the turn-table and a narrow ring 

 of the water-color applied. This will 

 dry quickly and look somewhat 

 opaque. The dammar cement is then 

 put on over the colored ring as above 

 directed, and it will be found that 

 the result is equal in beauty to the 

 celebrated shellac and anilin rings 

 of Mr. Merriman, without the danger 

 of the colors running in, as they often 

 will do when anilin or any color sol- 

 uble in the cement is used. When 

 glycerin or aqueous fluids are used, 

 it is necessary to apply the dammar 

 alone for a first coat ; the water-color 

 being applied over this, and a final 

 coat of gold-size or rubber cement 

 over all. Windsor & Newton put up 

 water-colors in little vials ready for 

 use, under the name of " liquid water 

 colors," by the use of which the stu- 

 dent may save himself the trouble of 

 rubbing down the cake. The porce- 

 lain ring, so much admired by some, 

 may be obtained by the use of white 

 water-color, or a little white zinc 

 rubbed up with gum-water, and ap- 

 plied as above directed. 



The centering of the cover may be 

 quickly and accurately accomplished 

 in the following manner. The slide 

 is placed in the jaws of the self-cen- 

 tering turn-table, a very narrow ring 

 of water-color is made upon its sur- 

 face with a finely pointed brush ex- 

 actly the size of the cover-glass to be 

 used. This will dry very quickly ; if 

 a number of slides are done at one 

 time, the first will be dry by the time 

 the third is done. The colored ring 

 being insoluble in any but watery me- 

 diums, the object maybe arranged on 

 the slide in alcohol, oil of cloves, car- 

 bolic acid, balsam or dammar, and it 

 will be easy to see when the edge of 

 the cover exactly coincides with the 

 edge of the colored ring. 



This ring will show through the 

 transparent ring used for finishing, 

 provided it be not covered by a 

 broader ring of color before the fin- 

 ishing ring of cement is applied, as 



suggested above. In any case it does 

 not detract from the appearance of 

 the slide. 



When mounting in glycerin or 

 watery fluids, it is always advisable to 

 use a cell of some kind, even though 

 it be no more than the shallowest ce- 

 ment cell, so that the cell, if properly 

 centered, is a guide for centering 

 the cover. From the fact that the 

 glass slides are not perfect rectangles, 

 it is necessary to place the same 

 corners in the same clutches of 

 the self-centering turn-table every 

 time a slide is manipulated on the 

 table. The simplest way to do this 

 is to mark one of the clutches with a 

 cross, and similarly to mark with a 

 file or writing diamond one corner of 

 each slide while cleaning it. 



Beck's ^^ Ideal" Microscope 

 Stand. 



The general design of this new 

 stand is the same as that of the well- 

 known " Economic," by the same 

 makers, with such alterations and ad- 

 ditions as the requirements of the 

 most advanced workers call for. The 

 instrument is wholly of brass, of ex- 

 cellent workmanship and finish, fif- 

 teen inches in height, with the stan- 

 dard length of tube ; the latter being 

 telescopic, the stand may be short- 

 ened to eleven inches, a most conven- 

 ient height when the instrument is 

 used in the upright position. The 

 base is a broad, heavy and perfectly 

 steady tripod, from which rises a 

 stout column, to which the body is 

 hinged so as to allow of its being in- 

 clined to any angle, with a stop at the 

 horizontal position. The body is of 

 the full standard size, using the same 

 eye-pieces as those furnished with 

 the " National " stands, and furnished 

 with an adapter, whereby objectives 

 with either the society screw may 

 be used, or those with the new broad 

 gauge or " Butterfield " screw, at 

 will. The coarse adjustment is made 

 by a rack and pinion of exquisite 

 smoothness, with sufficient length to 



