80 BULLETIN OF THE BUREAU OF FISHERIES. 
Many of the cheaper buttons are manufactured, really, in the way of by-products; 
that is, the shells must be bought for the making of good buttons, and the cost of the 
shell is chargeable to these profitable lines; it is better then to cut the remainder of 
the shell into very cheap grades than to throw it away. ‘There are times, however, 
after the demand for the poorer grades has been oversupplied, that it becomes actually 
necessary to discard waste shell, unless one is to manufacture at a serious loss. 
UTILIZATION OF WASTE PRODUCTS. 
In 1912, according to a statistical survey conducted by the Bureau, 55,671 tons of 
shells were used for the manufacture of buttons. Assuming that only 90 per cent of 
this material became a waste product in course of manufacture, we find 50,000 tons of 
waste material. This waste consisted principally of shells discarded after cutting out 
the blanks, but a considerable quantity was in the form of finely pulverized shells or 
dust generated in the processes of cutting, backing (or grinding), facing (or carving), 
and drilling. This dust is not permitted to escape into the air, as otherwise the atmos- 
phere of a factory would be unendurable. It is removed and concentrated by streams of 
water played on the shell while cutting and by a system of blowers and suction tubes 
connected with the several elements of finishing machinery. The dust is, therefore, 
made available for use. 
The uses of the waste material would be various were it not for the fact that other 
cheaper materials are available for many of the purposes for which it isadapted. For 
instance, the waste shell might be burnt for lime or used for the improvement of soils 
or for many common purposes. 
The principal use of the waste shell is for the production of poultry grit, for which 
purpose it is prepared by passing it through crushing machines, which divide it into the 
desired fineness; defective or broken blanks and unmarketable buttons also pass into 
the crusher (PI. XLI). ‘The waste shells are sometimes used also as road-building mate- 
tial. The shells are very hard and do not pulverize so readily as oyster shell. In this 
respect there are obvious disadvantages as well as advantages. 
The dust is useful in stock food, and in condition powders for hogs and poultry; 
it serves also appropriate purposes as an element in the manufacutre of artificial marble, 
tile floorings, etc. It is said to form a constituent of some jewelry polishes, soaps, and 
cleansing powders. The present market for dust is, however, nearly negligible. 
In 1912, 22,530 tons of crushed shell were sold, yielding $114,722, besides about 
10,500 tons of shell not crushed which were sold (probably largely to crushers) for $7,600. 
The sale of dust amounted to only 1,220 tons, bringing $3,470. The shell commanded 
about $5.50 per ton, and the dust about $4 per ton. In 1919 shell and dust yield, 
respectively, about $12.50 and $1 per ton. Both the shell and the dust possess certain 
exceptional qualities, and undoubtedly in time a better place in industrial uses will be 
found for them. 
USE OF SHELLS FOR NOVELTIES. 
The production of novelties from fresh-water mussel shells takes a wide variety of 
forms (PI. XLII). In 1912 there were six novelty works with an output valued at $61,800. 
From small whole shells or from portions of shells there were made such articles as watch 
charms, hatpins, stick pins, buckles, chains, cuff buttons, fancy buttons of all sizes and 
