These oils are soluble in alcohol, and very sparingly so in water. When dissolved in the former they constitute essences, a great variety of which are manufactured particularly at Paris, and are used as perfumes. Waters holding a small portion of aromatic oil, in solution, are called distilled tenters. A variety of these are used in medicioe.
2. The volatile oils when pure, pass off by evaporation, without leaving any stain on white paper. Hence a good test of the purity of these oils, is to let a drop fall on paper, and if an oily spot is left after the paper is warmed, it is certain that it has been adulterated by some fixed oil.
QUESTIONS ON VEGETATION.
What are the Elementary Substances of which VegetaBles are composed ?
What are the essential Organs of plants ?
What change does the Farinaceous Substance of seeds undergo during their germination?
What circumstances are necessary to the Healthy GerMination of seeds ?
flow is it shown that seeds will Not Germinate without
AIR?
IVhat u said of the germination of seeds in the exhausted receiver of an air pump ?
What effect does Oxygen have on the Germination of seeds ?
What is said of Van Helmonfs willow ?
What is ascertained concerning the Growth of Plants in Pure Water?
How is it proved that plants absorb matter from the soil?
What particular Ingredients must a Soil contain in order to make it Productive ?
Is it necessary that the Pood of plants should be Soluble in Water ?
What Change does the Sap undergo in the Leaves ?
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