414 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
rapidly applied. Whenever they are not satisfactorily symmetrical, a 
penknife may be used to bring them to the desired shape. 
It is now necessary to apply a finishing cement. For this purpose 
Bell’s cement has been found excellent, when modified as described 
below. The cement ring is finished at one application, enough being 
applied to produce a well-rounded ring. In a few hours the slide is ready 
for the cabinet. Bell’s cement has been found at times to work unsatisfac- 
torily, not fiowing freely from the brush, and forming large bubbles in the 
ring, particularly in a warm room. The addition of a very little chloro- 
form to the cement, and thorough mixing, produces a material that 
works smoothly, and dries with a satisfactory finish.” 
How to mount Objects in Motion for Examination by Polarized 
Light.* — Mr. George H. Curtis remarks : — “ None of the manuals I have 
consulted give directions for preparing slides of objects in motion for 
polariscope. Rubber cells are best and they should be about 1/16 in. 
deep and preferably for a 3/4 cover. The medium I use is Canada 
balsam thinned with a not quite equal bulk of spirits turpentine. Stir 
well together, and when dissolved filter through cotton. Cement the 
cells to slide with something not acted on by turpentine, say shellac, or 
sealing-wax in alcohol. Le Page’s liquid glue I think would answer, 
but I have not tried it. The fragments may be quartz, agate, sand, or 
anything not soluble in turpentine which polarizes well. One of the 
best is transparent gypsum or sulphate of lime. It is unnecessary to 
cement the cover on ; set aside for a couple of days and the balsam will 
get dry enough to hold it. Should you wish to ring them with Bruns wick 
black, size first with a coat or two of liquid glue made thin enough to 
flow, or the black will probably run in and spoil the slide.” 
Glycero-gum as a Mounting Medium.— Mr. C. C. Paris f finds a 
solution of gum arabic in glycerin preferable to Canada balsam or 
glycerin alone, as it is more transparent than balsam, with none of the 
objectionable features of glycerin. An object can be as well mounted in 
it without a cell as it can be mounted in balsam with a cell. The 
solution is made as follows : — Selected gum arabic, 2 oz. ; glycerin and 
distilled water, of each 1 J oz. ; thymol, 1 gr. Mix the glycerin and 
water, and dissolve tlie gum arabic in it by heating on a water-bath. 
After the solution has been effected add the thymol, and filter through 
absorbent cotton by the aid of a hot-water funnel. To have the solution 
perfectly clear the most transparent pieces of selected gum should be 
chosen. The solution will then be transparent and brilliant, and be 
found a successful medium for starches and pollen. It has shown no 
signs of deterioration after four months. 
Cleaning the Hands after working with Dammar Cements. J — A 
writer in the ‘ National Druggist ’ says : — “ As everybody knows who has 
worked at mounting, it is no easy matter to get the gummy and resinous 
material off the hands. Ordinary soap is of no avail, benzin is but little 
if any better, and aside from its costliness, benzol burns and dries the 
skin. I have used with a good deal of satisfaction a liquid soap made 
as follows : — Castile soap, shaved fine, 15 parts ; alcohol 95 j^er cent., 
* Micr. Bulletin and Sci. News, vii. (1890). 
t Western Druggist; Microscope, x. (1890) pp. 59-60. 
j The Microscope, x. (1890) pp. 25-6. 
