134 MISSOURI BOTANICAL GARDEN BULLETIN 
flowers are placed upon the purest of scentless cold lard, 
which is spread upon glass plates secured to wooden frames. 
Fresh blooms are daily added until the lard has become im- 
pregnated with the otto, the latter being extracted by agitat- 
ing in cold aleohol and evaporating. 
Another method of extracting perfumes is by hot macera- 
tion, the flowers being immersed and continually stirred in 
heated lard. The perfumed lard is afterwards separated from 
the flowers by filtration and pressure. The most modern 
method is by employing volatile solvents, by which, in a 
closed extraction apparatus, light petroleum spirit dissolves 
the essences, and after evaporation in a vacuum leaves them 
in a solid form. 
Sweet odors are generally classified under three headings : 
(1) floral, including all those obtained from sweet-smelling 
flowers, (2) aromal, those derived from all spices, herbs, and 
roots, (3) balsamic, obtained from such substances as resins, 
musks, etc. Various essences in compound are used as substi- 
tutes in the manufacture of certain perfumes. The heliotrope 
in concentrated form suggests the aroma of vanilla combined 
with that of bitter almonds. With this in mind the perfumer 
makes an excellent ‘‘extract of heliotrope’’ by combining a 
tincture of vanilla with a small proportion of otto of bitter 
almonds and sufficient rose and orange flower essences to give 
sweetness and floral character. A substitute for magnolia 
odor is obtained by mixing orange flower, tuberose, and violet 
essences, the addition of a touch of cedrat giving the pecu- 
liar sweetness characteristic of the flower. 
Chemical substitutes for perfumes, compounded by the 
chemist, enter greatly in the present-day market, especially 
in the cheaper perfumery. The laboratory rival of any nat- 
ural perfume may be a chemical artificial product which is 
absolutely identical with it, both physically and chemically. 
Among the sources of perfumery are the laboratory by- 
products of coal tar. 
The Garden collection of tropical perfume plants is located 
in the south side of the economic house and includes various 
species of jasmines, myrtles, winter-sweet, patchouli, orange, 
lemon, cinnamon, camphor, ete. The hardy flowers used for 
perfumes, such as tuberose, lavender, violet, ete., are grown 
in season in the economic garden south of the main conserva- 
tories. 
