The plan which I ultimately decided upon as the best which I had arrived at, was to shake up the oil with a little boiling water, and to leave the water in the bottle; a mucilaginous preparation forms on the top of the water, and acquires a certain tenacity, so that the oil may be poured off to nearly the last, without disturbing the deposit.  Perhaps cold water would answer equally well, were it carefully agitated with the oil and allowed some time to settle.  A consideration of its origin and constitution, indeed, strengthens this opinion; for although lemon otto is obtained both by distillation and expression, that which is usually found in commerce is prepared by removing the “flavedo” of lemons with a rasp, and afterwards expressing it in a hair sack, allowing the filtrate to stand, that it may deposit some of its impurities, decanting and filtering.  Thus obtained it still contains a certain amount of mucilaginous matter, which undergoes spontaneous decomposition, and thus (acting, in short, as a ferment) accelerates a similar change in the oil itself.  If this view of its decomposition be a correct one, we evidently, in removing this matter by means of the water, get rid of a great source of alteration, and attain the same result as we should by distillation, without its waste or deterioration in flavor.

I am, however, aware that some consider the deposit to be modified resin.[H] Some curious experiments of Saussure have shown that volatile oils absorb oxygen immediately they have been drawn from the plant, and are partially converted into a resin, which remains dissolved in the remainder of the essence.

He remarked that this property of absorbing oxygen gradually increases, until a maximum is attained, and again diminishes after a certain lapse of time.  In the oil of lavender this maximum remained only seven days, during each of which it absorbed seven times its volume of oxygen.  In the oil of lemons the maximum was not attained until at the end of a month; it then lasted twenty-six days; during each of which it absorbed twice its volume of oxygen.  The oil of turpentine did not attain the maximum for five months, it then remained for one month, during which time it absorbed daily its own volume of oxygen.

It is the resin formed by the absorption of oxygen, and remaining dissolved in the essence, which destroys its original flavor.  The oil of lemons presents a very great analogy with that of oil of turpentine, so far as regards its transformations, and its power of rotating a ray of polarized light.  Authorities differ as regards this latter property.  Pereira states that the oil of turpentine obtained by distillation with water, from American turpentine, has a molecular power of right-handed rotation, while the French oil of turpentine had a left-handed rotation.  Oil of lemons rotates a ray of light to the right, but in France a distilled oil of lemons, sold as scouring drops for removing spots of grease, possesses quite the opposite power of rotation, and has lost all the original peculiar flavor of the oil.  Oil of lemons combines with hydrochloric acid to form an artificial camphor, just in the same manner as does oil of turpentine, but its atom is only one half that of the oil of turpentine.  The artificial camphor of oil of lemons is represented by the formula, C_{10}H_{8}HCl; the artificial camphor of oil of turpentine by C_{20}H_{16}HCl.