Mr. English on Preservation of Plants. 73
I then tried petroleum last (i.e., after pressing) instead of
first. I found that some kinds of foliage did best in the
latter way, but flowers were most successfully dried first,
the petroleum being afterwards applied. This I found to
be the case almost by accident. I had laid some flowers
in the sun; of course they soon shrivelled and dried up,
but I was surprised with the brilliant colours they re-
tained. It occurred to me that heat and a powerful
absorbent of moisture might be successfully tried. I took
ordinary plaster-of-Paris, warmed to about 90 or 100 degrees
(F.), and embedded the fresh flowers in it, shaking the
plaster carefully down on the plants. This plan answered
admirably. Small plants were preserved in less than twelve
hours; larger species took longer in proportion to the
amount of moisture in their tissues. When taken out of
the plaster the plants presented a very dusty appearance,
and if left in it too long they became somewhat
brittle, but on being laid aside in the air for a time they
soon relaxed. They were then brushed with a camel's-hair
pencil, and petroleum carefully applied with a brush.
Such is the history of the specimens now exhibited, show-
ing well the natural form and colour. Beds and purplish-
reds, however, came out too purple. I overcame this diffi-
culty at last by immersing the dried plants in the vapour
of hydrochloric acid. About a teaspoonful of acid is put
into a wide-mouthed bottle or glass cylinder, and the plants
suspended by the stalks, so as not actually to touch
the liquid acid; when the proper shade of colour appears
they must be quickly removed.
Plants thus dried can be pressed as usual for the herba-
rium sheets, or exhibited in cabinets, like collections of
insects, and would probably be found extremely useful for
educational purposes. Some of the more rigid plants can
be mounted under glass shades, and they then have a very
pleasing appearance, but exposure to the light is very likely
to fade them.
It may be well to add that, about three weeks since, a
gentleman (an artist) called upon me. He had been travel-
ling in North America, and when in New York he was