ETHERS AND ESTERS. 527 



3. Heat in a dry test-tube a small quantity of fat with an equal 

 portion of potassium bisulphate. Acrolein is formed and recognized 

 by its odor. 



4. Heat about 2 grammes of fatty acids with 100 c.c. of water and 

 enough sodium carbonate to dissolve the fatty acids. A solution of 

 sodium soap is formed, of which use a few c.c. for each of the follow- 

 ing reactions : 



a. Heat with an excess of hydrochloric acid ; fatty acids are lib- 

 erated. 



6. Add calcium chloride solution ; insoluble calcium soap is formed, 

 and the solution does not foam on shaking. 



c. Add lead acetate solution ; a white precipitate of an insoluble 

 lead salt (lead plaster) is formed, becoming sticky on heating. 



d. Add some olive oil and shake well ; a homogeneous milk-like 

 mixture i. e., emulsion is formed. 



Wool-fat, Lanolin, Adeps lanse. This is the fat, or a mixture of fats, 

 found in sheep's wool and obtained by treating the wool with soap-water, and 

 acidifying the wash liquor, when the fats separate unchanged. These fats 

 differ from the fats spoken of above in so far as the alcohol present is not 

 glycerin, but an alcohol, or rather two isomeric alcohols of the composition 

 C 26 H 4:! OH and known as cholesterin and isocholesterin. These alcohols, which 

 are white, crystalline, fusible substances, when in combination with fatty acids 

 form the compound ethers known as lanolin. 



Lanolin is a yellowish-white (or, when not sufficiently purified, a more or 

 less brownish), fat-like substance, having the peculiar odor of sheep's wool and 

 fusing at about 40 C. (104 F.), forming an oily liquid. Unlike true fats, 

 lanolin is capable of mixing with twice its weight of water or aqueous solutions 

 and yet retaining its fatty consistency ; it is, moreover, much less liable to de- 

 compose than fats, and it is this property and its power to mix with aqueous 

 solutions which have rendered lanolin a valuable agent in certain pharma- 

 ceutical preparations. Official is also hydrous wool-fat, the purified fat mixed 

 with not more than 30 per cent, of water. 



QUESTIONS. Explain the constitution of simple and mixed ethers ancfr 

 esters. To what inorganic compounds are they analogous? State the general 

 processes for the formation of ethers and esters. What is the composition of 

 ethyl ether ? Explain the process of its manufacture in words and symbols, 

 and state its properties. How is acetic ether made, and what are its proper- 

 ties? What is sweet spirit of niter, and how is it made? State the general 

 composition of fats and the chief constituents of tallow, butter, and olive oil. 

 What is the solubility of fats in water, alcohol, and ether; how do heat and 

 oxygen act upon them ; what is the cause of their becoming rancid? Explain 

 the composition and manufacture of soap, and state the difference between hard 

 and soft soap. How are ammonia liniment, lime liniment, and lead plaster 

 made, and what is their composition ? What is the source of lanolin ; what 

 are its constituents and properties ? 



