are not as high in this test as are the Mediterranean Deepwater sponges, 

 but -with the number of samples run, there was no significant difference 

 between the Inshore and Rock Island sponges. The Inshore, Rock Island, 

 and Mediterranean sponges, however, have a higher cleanability than 

 have the remaining three. These three — Hudson Grass, Florida Yellow, 

 and Anclote Grass — give practically the same low value of cleanability. 

 Again, it must be remembered that other factors enter into the choice 

 of a sponge. Grass sponges, for instance, drain out a lot more water 

 when tipped on end. This property would apparently make them easier 

 to clean, but the same modification of the test would work against them 

 in water-holding power. The drained water would drastically reduce the 

 maximum amount of water that they could be said to hold. 



D. Stiffness tests (table 16) indicate that there are three groups 

 statistically different from each other. The Mediterranean Deepwater 

 are the least stiff (in other words, the softest), followed closely by 

 a tight group composed of Inshore, Rock Island, and Mediterranean Ben- 

 gasi. Bridging the gap, but not distinctly different from the stiff est 

 group, is the Anclote Grass sponge. The Florida Yellow and the Hudson 

 Grass sponges are the other stiff sponges. 



Table 16.— Stiffness 



Type of sponge 



Ifamber of 

 sponges tested 



Average 



Standard 

 deviation 



Fiducial 

 limits 







Percent 



Percent 



Percent 



Hudson Grass 



25 



U0.7 



15.8 



3U.2-U7.2 



Florida Yellow 



2U 



Ul.l 



10.6 



36.7-U5.6 



Anclote Grass 



2U 



32.1 



13.2 



26.5-37.7 



Mediterranean Bengasi 



25 



22.6 



5.7 



21. -25. 



Rock Island Sheepswool 



28 



20.9 



3.6 



19.5-22.3 



Inshore Sheepswool 



26 



20.6 



2.7 



19.5-21.7 



Mediterranean Deepwater 



28 



16.6 



U.5 



1U.9-18A 



E. Elasticity is important. Whether the sponge be stiff or soft, 

 the user wants it to regain most of its shape immediately. Under the 

 carefully controlled conditions of these tests, both soft and stiff 

 sponges can be said to have the same elasticity with the exception of 

 both of the Mediterranean sponges (table 17); for instance, Inshore, 

 Rock Island, Florida Yellow, and Anclote Grass sponges all have the same 

 high elasticity. Only the Hudson sponges recover more of their height 

 immediately. The Mediterranean Deepwater sponges are the least elas- 

 tic, with the Bengasi having a definite superiority over the Deepwater 

 sponges. Elasticity may be an important property in determining the 

 preference for the domestic sponges by several of the trade groups, 

 such as window washers. 



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