958 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



opaque. The dammar cement is then put on over the coloured 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 colours running in, as they often will do 

 when anilin or any colour soluble in the cement is used. When 

 glycerine or aqueous fluids are used, it is necessary to apply the 

 dammar alone for a first coat, the water-colour being applied over 

 this, and a final coat of gold-size or rubber cement over all. Windsor 

 and Newton put up water-colours in little vials ready for use, under 

 the name of " liquid water-colours," by the use of which the student 

 may save himself the trouble of rubbing down the cake. 



The centering of the cover may be quickly and accurately accom- 

 plished in the following manner : — The slide is placed in the jaws of 

 the self-centering turntable, a very narrow ring of water-colour is 

 made upon its surface with a finely pointed brush exactly 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 coloured ring being insoluble in any but water 

 mediums, the object may be arranged on the slide in alcohol, oil of 

 cloves, carbolic acid, balsam, or dammar, and it will be easy to see 

 when the edge of the cover exactly coincides with the edge of the 

 coloured ring. This ring will show through the transparent ring 

 used for finishing, provided it be not covered by a broader ring of 

 colour before the finishing ring of cement is applied, as suggested 

 above. In any case it does not detract from the appearance of the 

 slide. 



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 turntable every time 

 Fig. 227. 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. 



Preserving Cover-glasses.* 

 — Mr. C. E. Hanaman keeps 

 upon his work-table one or 

 more grooved blocks like that 

 shown in Fig. 227, in which 

 cover-glasses that have been 

 selected for immediate use are 



supported on their edges, and from which they can be easily taken 



by the forceps. 



It is also convenient, when a number of covers have been cleaned, 



to keep them in drawers or boxes filled with narrow strips of new 



Amcr. Mon. Mior. Journ., ii. (1881) pp. 142-3 (2 figs.). 



