NOTES AND MEMORANDA. 
161 
object should lie in the dye from three to five hours, Ferns, buchu, 
and leaves of similar structure, may be stained in from two to three 
hours. When the hue has become tolerably pronounced, the object is 
placed in common alcohol, where it is immediately brushed with care, 
yet thoroughly, and passed to absolute alcohol, to lie from one to two 
hours. Changing the alcohol once is advantageous. Then to oil 
of cloves, as above, and mounted. Of the anilines, blue is the best 
colour to use alone. This dye is prepared by putting four grains of 
the powder in one ounce of common alcohol, previously triturating the 
powder thoroughly. If the powder does not readily dissolve, add one 
drop of nitric acid. It is better for the colour to use no acid, as that 
ultimately produces a reaction ; but some brands of aniline are so far 
insoluble in alcohol as to make it necessary to introduce a quickening 
agent. It is true, all the anilines readily dissolve in water ; but ho 
who has used a water dye for colouring leaves is very likely willingly 
to leave the subsequent use of it to others. Eernove the object from 
the alcohol to the dye, and let it remain there until, on examination, 
it is found to have reached the desired depth of hue; then, after 
letting it drip a moment, place it in oil of cloves, to be mounted like 
the others. I apply oil of cloves by dropping it fresh upon the 
object until the saturation is complete. Double Staining. — My 
attention was first called to the possibility of distributing two or 
more colours through vegetable tissue by the result of staining a leaf 
in freshly mingled aniline blue and poke-berry juice. The hairs 
were purely blue, while the other portions were of different shades of 
red. Not duly appreciating my discovery, I neglected it for several 
months. I ultimately instituted a series of experiments with various 
forms of mingled dyes, producing results so entirely satisfactory, that 
I have never since stained with a single dye. My method, now 
perfected by long practice, is this, for anilines : The required 
quantity of dye is dropped into a jar, in the proportion of one drop of 
red to three, four, or five — in some rare cases even eight drops of 
blue, both dyes Icing of the same strength. For tissue which 
rapidly absorbs colour, such as the ferns, the drosera, the pinguicula, 
and the like, I prefer one to three ; for tissue that takes colour 
slowly, as laurus, aucuba, oleander, &c., the proportion of blue should 
be greater. It is idle to try to give exact proportions, as the 
experimenter will soon perceive. If the dye is of full strength, four 
grains to the ounce, the first class of objects are sufficiently coloured 
in one minute ; the second class may remain in from fifteen minutes 
to half an hour. They should, however, be carefully watched. I 
prefer diluting the dye by adding alcohol, eight drops to one of the 
dye, and strengthen the latter by dropping in fresh dye from time to 
time in the proportion mentioned at the beginning. The required 
hue being reached, treat the objects as these in one colour are treated, 
except that, if there seem to be too much red, immerse the object for a 
short time in absolute alcohol. It is well always to examine an object in 
oil of cloves under a moderate power. If the surface be very tender, 
this should be done without a cover. After the absolute alcohol, return 
to clean oil of cloves, to be mounted after a minute or two. Sections are 
