DOUBLE STAINING. 129 
(3) preparing for staining, (4) staining in carmine, (5) staining in 
green. ‘These processes will be described serzatim. 
Vegetable sections may be bleached in various ways. When 
alcohol is used, no washing afterwards is necessary ; but when acids 
are employed, all traces of the same must be entirely removed, so 
as to prevent crystallisation taking place after the sections have 
been mounted. But as there are objections to the use of alcohol, 
preference is to be given to a solution prepared in the following 
manner :—Dissolve in half a pint of water one ounce of fresh 
chloride of lime, and whilst the latter is in partial suspension, add 
about fifty drops of sulphuric acid.* Allow the solution to stand 
for about half-an-hour, or until all insoluble particles have entirely 
subsided, after which syphon off the clear liquid, and preserve in a 
stoppered bottle in a dark place. This latter precaution is impera- 
tive, because if the solution were exposed to the sun’s rays its 
- bleaching properties would be destroyed by a liberation of hydrogen 
which would combine with the chlorine from its state of inactive 
combination in the water. 
After the sections have been bleached, which process it should 
be observed is completed when all colour has been demolished, 
they are to be washed in one or two waters and then soaked in a 
solution of sulphite of soda, composed of one part of sulphite to 
twenty parts of water, and finally washed in from ten to fifteen 
changes of warm water, for the purpose of removing any remaining 
traces of the reagents. 
After this, in order to obtain deep colours, the sections are to be 
steeped in a mordant composed of ten per cent. solution of alum 
and water for twenty-four hours, at the end of which time they will 
be ready to be placed in the first staining fluid, the formula for 
which is as follows :— 
Garnier. joer tw staetathe wees «35 15 grs 
PATUMLOMIA as. deowsceeeuaccets<' Se 15 grs 
SRV VALCES serves cieb achat nae wa cins(csathents 2 OZS. 
The carmine is to be dissolved in the ammonia over the flame of 
a spirit lamp, the water added next, and the fluid filtered through 
fine muslin before it is used. 
Immerse the sections in this stain for six or eight hours, then 
take them out, and wash them in not more than two changes of 
water, and finally transfer them to the green stain, for which 
take,— 
WB evi oy OS (een 5 gers. 
Aljasolute-Alcohol ......45 6.422 0% TO% 
* Hydrochloric acid would be better adapted for use than sulphuric, inas- 
much as sulphate of lime, often difficult to get rid of, is not formed by this 
addition.—ED. 
