CHAPTER XII 



HOUSEHOLD CHEMICALS 



Chemistry. Automobiles, airships, subways, canals such 

 as the Panama Canal, and suspension bridges, show man's 

 progress in mechanical construction. But man's mechanical 

 inventions have been equaled by his chemical researches and 

 discoveries, and by the application he has made of his knowl- 

 edge of substances. 



The plain cotton frock of our grandmothers had its death 

 knell sounded a few years ago, when John Mercer showed that 

 cotton fabrics soaked in caustic soda assumed under certain 

 conditions a silky sheen, and when dyed took on beautiful and 

 varied hues. The demonstration of this simple fact laid the 

 foundation for the manufacture of a variety of attractive dress 

 materials known as mercerized cotton. 



Possibly no industry has been more affected by chemical 

 discovery than that of dyeing. Those who have seen the 

 best masterpieces in painting, or reproductions of them, know 

 the softness, the mellowness, the richness of tints employed by 

 the old masters. But if we look for the brilliancy and variety 

 of color seen in our own day, the search will be fruitless, because 

 these were unknown until half a century ago. Up to that 

 time, dyes were few in number and were extracted solely from 

 plants, principally from the indigo and madder plants. But 

 about the year 1856 it was discovered that dyes could be ob- 

 tained from coal tar in much greater variety and in purer form. 

 This chemical production of dyes has now largely supplanted 

 the original method, and the industry has grown so rapidly that 



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