176 PRACTICAL LESSONS IN SCIENCE. 



of the sugar is made from the juice of the sugar-cane, while in 

 Europe the juice of the sugar-beet is generally used. In the 

 manufacture of cane-sugar the canes are crushed between 

 grooved iron rollers and the juice mixed with the milk of lime is 

 boiled in open pans. The lime neutralizes the acids and hardens 

 some of the impurities; the albuminous matters, hardened by 

 heat, entangle these impurities and rise as a thick scum. The 

 scum is removed and the clear liquid remaining is evaporated to 

 such a consistency that on cooling it separates into two parts, 

 one crystalline, called brown sugar, the other unerywtalline, 

 called molasses. These products are purified, refined and con- 

 verted into the various grades of sugar and sirup of commerce. 



Sugar melts to a colorless liquid which on cooling forms an 

 amber colored mass called barley sugar. When heated to about 

 400 F. sugar is changed to a dark brown substance called cara- 

 mel, which is soluble in water, being used for coloring sauces, 

 gravies, wines, brandies, etc. 



The white of an egg is a typical form of an interesting and 

 important substance called albumen, which is found in all ani- 

 mals and vegetables. It is composed of carbon, hydrogen, 

 oxygen, nitrogen and sulphur, but the chemical formula is not 

 fully known. It seems to be about C 108 H 169 N 27 034S. It is found 

 in the blood and milk and in lean meat; it is associated with 

 starch in plants, as the gluten of wheat, and the legumin of 

 beans. The elements which compose albuminous compounds are 

 not firmly bound together; they break up and decompose very 

 readily, and in many cases promote change and decomposition 

 in other substances. 



In addition to the starch, seeds and grains contain some form 

 of albumen. When placed in warm moist air the albumen 

 takes up oxygen forming carbon dioxide, and a substance, con- 

 taining carbon hydrogen, nitrogen and oxygen, called diastase. 

 Diastase has the power to set up changes by which the insoluble 

 starch is converted into the soluble glucose, which can be used 

 by the growing plant as food. If the seed is kept dry or cool it 

 will remain dormant for thousands of years, but expose it to air, 



