FRESH-WATER MUSSELS AND MUSSElv INDUSTRIES. 71 



The classification of shells by size and character has obvious advantages for adap- 

 tation of material to particular grades of buttons and to uniform speeds of machinery. 



Soaking. — After classifying, the shells are placed into large metal tanks or vats, 

 each holding about a ton, or sometimes into barrels. The containers are then filled 

 with water, in which the shells are allowed to soak for a week or more. The process 

 is intended to soften the material, which would otherwise be too hard on the saws, as 

 well as so brittle as to chip and yield blanks with rough edges. The smaller sizes of 

 shell may simply be put into damp cellars, sprinkled, and covered with wet cloths. 



Curiously enough, there is a difference of opinion among manufacturers as to the 

 merits of this treatment, the contrary view being held by some that the material works 

 better if not soaked, but simply sprinkled, before cutting. The custom of soaking is one 

 that is generally desired by the cutters, however, since it is held to lessen the labor of 

 resharpening the saws. 



An obvious but probably unnecessary disadvantage of the soaking process consists 

 in the fact that the shells as marketed have small bits of meat attached, so that after 

 soaking the water may become more or less foul. In handling the shells scooped from 

 the vats there is the possibility of contamination in the event of abrasions upon the 

 hand. This is undoubtedly the cause of an infection to which cutters are more or less 

 liable. The addition of an antiseptic compound to the water of the vats should be a 

 universal feature of this process. 



SAWING OR BLANK CUTTING. 



The Machine. — ^The cutting machine is essentially a lathe fitted, on the one hand, 

 with a tubular saw of the necessary diameter to obtain the required size of button, and, 

 on the other hand, with a wooden plug and a ratchet handle or lever for gradually forcing 

 the rough shell against the rapidly rotating saw (Pi. XXXV, fig. 3). The shell is held 

 in position either by tongs or by the hand protected with a mitten. During the cutting 

 process small jets of water are directed against the shell to keep it, as well as the saw, cool 

 and also to prevent the production of troublesome and injurious dust (PI. XXXVIII, 

 fig. 2). Successive blanks as they are cut are crowded through the tubular saw to fall 

 into a receptacle below. When the desired blanks are removed, the shell is thrown 

 into a bucket or box to be subsequently dumped upon the shell heap, unless the shell 

 is to be passed to another machine for a second cutting of smaller and thinner blanks. 

 The cutting machine, including the saw, is about the only one of the many used in 

 button factories on which no radical improvements have been made since it was first 

 introduced and adapted to the fresh-water shells. The original invention may or may 

 not be the best solution of the problem, but as yet none of the machines put forth 

 as improvements has earned an established place in manufacture. 



The saws must be made of specially hardened steel, and are obtainable from only 

 a few shops. When received from the factory, each saw is simply a rolled cylinder 

 tapering at one end, being without teeth at this stage (PI. XXXVII, fig. i). They are 

 made of different tempers as extra-hard, hard, regular, soft, and very soft, for adapta- 

 tion to the varied texture of the material to be cut. 



The sizes of the buttons are determined by the inner diameter of the cutting end 

 of the saw, and the unit of button measure is one-fortieth of an inch, called a line. But- 

 tons from fresh-water shells vary in size from 14 to 40 lines (from about one- third of an 



