Tue Microscope. 11 
oxalic acid and transferred through successively higher grades of 
alcohol and mounted. 
PICRO-CARMINE, 
The most extraordinary methods have been devised for pre- 
paring this really simple dye, but the writer has found no ad- 
vantage whatever in those whose manufacture involves much 
labor and time. The following by Dr. Mayer answers as well 
as any and is easily made: 
Two grammes of carmine are placed in twenty five cubic 
centimeters of water and enough ammonia added to dissolve 
the carmine. The whole is kept warm over a water bath until 
the excess of ammonia has evaporated and the fluid is a deep 
cherry redin color. Itis then cooled and filtered. To the filtrate 
is added a saturated solution of picric acid in water until a 
precipitate begins to be formed. (About four volumes of the 
acid to one of the carmine). After again filtering it is ready for 
use, or— 
To a solution made of 1 grm. carmine, 4 grm. of ammonia 
and 200 c. c. of water, add 5 gramsof picric acidin crystals. Ag- 
itate well and decant the supernatant liquor. This is allowed 
to remain for several days with occasional stirrings, then evap- 
orated to dryness in a water bath. To every 2 grams of the 
residue add 100 c. c. of water. 
If the sections are treated with “‘ acid glycerine,” (see under 
alum carmine), before staining with picro-carmine, the color- 
ation is sharper and more truly differential. 
PICRO-LITHIC-CARMINE, 
Lithium carbonate, saturated solution in water 100 ec. ec. 
Tern Cee oa = 22 a ee ee eS 23 grms. 
To the above, made into a solution by heat, is added 2 or 3 
parts of a saturated solution of picric acid in water. Used the 
same as the preceding. 
PALLADIUM CHLORIDE AND CARMINE, 
A 4 per cent. aqueous solution of the chloride of palladium 
is used for about 10 minutes, or until the section is of a straw 
yellow color. The specimen is then transferred to an ammonia 
carmine solution until red, washed and transferred through alco- 
hol and clove oil to balsam. 
