FRESH-WATER MUSSELS AND MUSSEL INDUSTRIES. 89 



attention of many manufacturers and mechanics. Remarkable improvements in button- 

 making machinery and systems of management have taken place in recent years. 

 Perhaps conspicuous advances in the future may be made, not only in such improvements 

 of management and existing machinery as are always to be expected, but in the inven- 

 tion of an efficient machine for blank splitting and in the perfection of bleaching processes; 

 also in the greater utilization of unavoidable waste. 



In 191 2 there were 196 separate plants employing mussel shells in manufacture. 

 Of this number 153 plants were devoted to cutting only, while 36 factories engaged in 

 finishing and grading. Of these latter 20 included cutting rooms, also, and thus comprised 

 all the processes of manufacture. In addition there was a single branch plant devoted 

 exclusively to the grading of buttons. There were 34 shell-crushing plants, of which 32 

 were connected with button factories, and there were 6 novelty works. These establish- 

 ments were located in 20 States as follows: Alabama, Arkansas, Kansas, Kentucky, 

 Illinois, Indiana, Iowa, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New 

 Jersey, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, West Virginia, and 

 Wisconsin. 



The industry is peculiarly American. The material has until recently been obtained 

 in no other country, and the machinery and methods are largely of American design and 

 development. 



