BULLETIN 39, UNITED STATES NATIONAL MUSEUM. 



[90] 



to project about one-fourth iucli, serve to hold the block to the cork 

 bottom of the case or drawer iu which it is to be placed. The method 

 of use is simple and readily seen from the accompanying figures^ which 

 represent the block from all sides. 



The advantages of this system are the ease and security with which 

 the block can be placed in or removed from a box; the ease with which 

 a> vial can be slipped into or removed from the wire clamps ; the security 

 with which it is held, and the fact that practically no part of the con- 

 tents of the vial is obscured by the holder — the whole being visible from 

 ^bove. 



The beveled ends of the block may be used for labeling, or pieces of 

 clean card-board cut so as to project somewhat on all sides may be used 

 for this purpose, and will be held secure by the pins between the block 

 and the cork of the drawers. 





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4 



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Fig. 112. — Vial holder; 1, block, with vial, beveled on all sides : 2, do., beveled only on ends ; 3, block, 

 ondview; 5, do., section; 4, 6, do., side views; a, block; 6, spring- wire clamps ; c, beveled ends of block; 

 d, pointed wire nails ; e, point of insertion of clamp. (Lettering on all figures corresponds.) 



The use of rubber stoppers in this country was first instituted by Dr. 

 H. A. Hagenin connection with the Cambridge biological collection, 

 and he has made some very careful records to determine the durability 

 of such stoppers. Prom an examination of some seven thousand vials 

 with rubber stoppers, two-thirds of which had been in use for from ten 

 to twelve years, he comes to the conclusion that less than one in a 

 thousand gives out every year after twelve years' use, and in the first 

 six years probably only one out of two thousand. Stoppers of large 

 size keep much longer than those of small size. American rubber 

 stoppers are all made of vulcanized India rubber and have the disad- 

 vantage of forming small crystals of sulphur about the stopper, which 

 become loosened and attach themselves to the specimens. It is supposed 



