118 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
wrinkles, taking special care not to melt the paraffin suri’ounding the 
preparations. As they are perfectly flat, drain off the snperahimdant 
fluid, and stand the slide on end to dry. The best results are obtained 
if the slide is allowed to stand over-night to dry spontaneously. After 
the sections are dry, the whole is immersed in turpentine or other 
solvent to remove the j)araffin, then into alcohol to remove the turpentine, 
tbence into a two per cent, solution of potassium bichromate for five 
minutes, wdiich renders the gelatin fixative insoluble. After washing 
tbe slide in w^ater to free the section from bichromate) w'hich, by the 
way, will not injure the most delicate tissue or interfere with any stain- 
ing process) the section may be stained as desired. For sections stained 
in mass the soaking in bichromate is unnecessary, but if, after mount- 
ing, the stain sliould prove insufficient, tbe sections may be readily 
restained by removing the cover-glass, soaking off the balsam with a 
suitable solvent, transferring to alcohol and then rendering the fixative 
insoluble by soaking in bichromate before immersing in the stain. This 
process is especially valuable in staining tissues for bacteria, as it 
admits of extremely thin sections being placed on the slide free from 
wrinkles, and does not blister by prolonged soaking in aqueous solutions, 
as frequently happens in Scliiillibaum’s clove-oil-collodion process, the 
method in general use for staining sections on the slide.” 
Use of Oil of Cloves.* — Mr. W. Hatchett Jackson points out that 
sections to wdiich oil of cloves has been added and which have turned 
milky are not, as is often supposed, useless. If a small quantity of oil 
is poured on the sections and tbe whole gently warmed for a short time, 
the milkiness disappears. If it does not disappear at once the oil in 
the slide should be poured off, fresh oil added, and the heating repeated. 
The milkiness is due to a combination between the essential oil and 
a small residuum of water, and this is readily soluble by the aid of 
warmth in an excess of the essential oil. Kepeated soaking in absolute 
alcohol effects tbe same end. 
Cement for fixing down Glycerin Preparations.f — The cement 
recommended by Dr. S. Aj)athy is said to be hard, without brittleness, 
and not to run under the cover-glass. 
It is made of equal parts of hard paraffin, melting-point 60° C., 
and commercial Canada balsam. The mixture is heated in a porcelain 
dish until it assumes a gold yellow hue, and a resinous odour is no 
longer perceived. When cold the mixture forms a hard mass, which 
requires to be heated for use and to be laid on with a glass rod or brass 
spatula. The metal spatula is then heated and run round the edge to 
finish it off. 
(6) Miscellaneous. 
Detection of Blood-stains. | — Dr. C. Charles remarks that, according 
to Linassier, tbe most sensitive sijectroscopic reaction of blood is that 
given by reduced haematin. 
The blood- stain is dissolved in water and examined for the spectrum 
* Zool. Anzeig., xii. (1889) pp. 630-1. 
t Zeitscbr. f. Wiss. Mikr., vi. (1889) pp. 171-2. 
j Amer. Moii. Micr. Journ., x. (1889) p. 236, from ‘ Tbe Dosimetric Medical 
Eeview,’ July 1889. 
