EUGENOL^ — FATS 345 



solution of chloral hydrate. At 130° C. all ethereal oils may be 

 driten from sections, while the fatty oils remain behind. Ether- 

 eal oils are only slightly soluble in water, but they impart their 

 smell strongly to it. They are easily soluble in ether, chloroform 

 and fatty oils. The spot produced on paper by ethereal oils 

 soon disappears. They agree with the fatty oils in being browned 

 or blackened by osmic acid and in being stained by alcannin 

 and cyanin. 



Eugenol, CgH3.OH.OCH3.C3H5. — Eugenol occurs in clove 

 and pimento oil. When sections containing either of these oils 

 are treated with a concentrated solution of potassium hydrate, 

 long columnar or needle-shaped crystals of potassium caryophyl- 

 late are produced. When sections of cloves are used, they often 

 become covered by the forming crystals. 



Fats and Fatty Oils. — These are insoluble in cold and hot 

 water, and, with the exception of castor oil, hardly ' soluble in 

 alcohol, but readily soluble in ether, chloroform, benzol, ethereal 

 oils, aceton and wood spirit. They make a spot on paper which 

 does not disappear, as in the case of ethereal oils. Most fats and 

 fatty oils are colored brown or black by i per cent, osmic acid. 

 When a drop of fat or fatty oil is placed on a glass slide in a drop 

 of a mixture of equal parts of concentrated potassium hydrate 

 and ammonia, the oil becomes saponified, and may assume a 

 form like a bunch of grapes, or it may be partly or wholly changed 

 into clusters of soap crystals. Vapor of hydrochloric acid has 

 been used to distinguish between ethereal and fatty oils. A 

 large and a small glass ring, such as are used for hanging-drop 

 cultures, are 'cemented to a glass slide, the small one being shal- 

 lower than the large one, and placed Within it concentrically. 

 Hydrochloric acid is placed into the space between the rings, 

 and the sections to be tested are placed on a coverglass in a drop 

 of glycerine containing a strong solution of sugar.' 



The coverglass is then inverted and placed on the larger ring. 

 After the vapor of hydrochloric acid has had time to act, any 

 ethereal oil present in the sections will take on the form of bright 

 yellow drops which "finally disappear. Fatty oils do ' not form 



