previously existing, and simply separated in the process of distillation), or whether they are not rather produced by the heat and chemical change in the process of distillation. The continued application of an elevated temperature alone is sufficient to effect changes in the constitution of many organic products, evolving new bodies not before existing in the original substance.
PROPERTIES OF THE DISTILLED OILS
Exposed to the severest cold of the past winter, all the oils obtained in this distillation remained fluid. Only the last two or three appeared at all stiffened by a cold of 15° below zero, while the first three or four products of distillation retained a perfect degree of fluidity. Exposed to air, as I have said, they suffer no change. The chemical examination of these oils showed that they were all composed of carbon and hydrogen, and probably have these elements in the same numerical relation. When first distilled they all had an acid reaction, due to the presence of a small quantity of free sulphuric acid, derived from the crude oil. This was entirely removed by a weak alkaline water, and even by boiling on pure water. Clean copper remained untarnished in the oil which had thus been prepared, showing its fitness for lubrication, so far as absence of corrosive quality is concerned. The oils contain no oxygen, as is clearly shown by the fact that clean potassium remains bright in them. Strong sulphuric acid decomposes and destroys the oil entirely. Nitric acid changes it to a yellow, oily fluid, similar to the changes produced by nitric acid on other oils. Hydrochloric, chromic, and acetic acids do not affect it. Litharge and other metallic oxyds do not change it, or convert it in any degree to a drying oil. Potassium remains in it unaffected, even at a high temperature. Hydrates of potash, soda, and lime are also without action upon it. Chloride of calcium and many other salts manifest an equal indifference to it. Distilled with bleaching powders (chloride of lime) and water in the manner of producing chloroform, the oil is changed into a product having an odour and taste resembling chloroform. Exposed for many days in an open vessel, at a regulated heat below 212°, the oil gradually rises in vapour, as may be seen by its staining the paper used to cover the vessel from dust, and also by its sensible diminution. Six or eight fluid ounces, exposed in this manner in a metallic vessel for six weeks or more, the heat never exceeding 200°, gradually and slowly diminished, grew yellow, and finally left a small residue of dark brown, lustrous-looking resin, or pitchy substance, which in the cold was hard and brittle. The samples of oil employed were very nearly colourless. This is remarkable when we remember that the temperature of the distillation was above 500°F. The oil is nearly insoluble in pure alcohol, not more than 4 or 5 per cent, being dissolved by this agent. In ether the oil dissolves completely, and on gentle heating is left unchanged by the evaporisation of the ether. India-rubber is dissolved by the distilled oil to a pasty mass, forming a thick, black fluid which,
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