— 338 On Preserving Organic ——— 
Arr. XIII. —Ona New and Effectual Method of Pride 
% Specimens of Organic Nature, and of obviating the Blanch- 
ing Infiuences of Light, and the Depredations of Insects ;— 
most Advantageously Applicable to the Formation and Un- 
limited Preservation of a Hortus Siccus, or Museum of Dried 
_ Planis ; by Joun L. Rippety, M. D., Professor of Chemistry 
and Materia Medica, in the Medical College of Louisiana. 
- Corpora non agunt nisi i aint soluta.” 
Ir is conceded, I believe, that light exerts an influence in chem- 
ical changes, by modifying or exacting the inherent electrical en- 
_ ergies of material particles. This influence has been observed 
times innumerable by every one, in the blanching or fading of 
organic colors. © Few, I apprehend, could be found, who would 
be willing, upon the first proposal, to believe in the possibility of 
easily and completely averting this fading power of light, and of 
conferring immutability upon the organic tints which are con- 
sidered as most delicate and evanescent. 
The possibility of so doing may perhaps be made theoretically 
to appear, thus :—The particles of an absolutely solid body can 
suffer no change, because'they are inter se immovable. A with- 
ering leaf; exposed to air and light, fades and decays, because 
there is moisture present. Liquid water fills myriads of its in- 
mebaibie pores and intercellular spaces. The leaf may be dry ex- 
ee it may be apparently dry within ; yet-it is really 
bued with more or less of water. - “This water may give fluid- 
ity to the fading coloring matter, either by immediate solution, or 
by becoming impregnated with acid substances. But it is chiefly 
by absorbing, and thus giving liquidity to oxygen gas from com- 
mon air, that it contributes to change. © Besides, it is favorable to 
' chemical action, by standing ready to dissolve and remove some 
or all of the eliminated products. Water, moreover, may exert 
an indirect agency in hastening organic changes, by favoring the 
existence of insects and animalcules. Light renders the chem- 
_ ical affinities concerned more active, and thereby soon accom= 
_plishes changes which time and other circumstances would ac- 
complish without it. Those conditions only, on which the 
power of assuming -the liquid state me ngs are essential. Re- 
- move = and no or cali occur. 
