STORAGE BOTTLES 363 



cork, are very useful and convenient for small speci- 

 mens. All bottles should have wide mouths, and the 

 1 ounce (30 c.c), 2 ounce, 3 ounce, and 4 ounce sizes 

 are recommended. 



Some wide-mouthed bottles are sold with a cork 

 fastened on to a wooden cap. They look very neat 

 and nice, but have proved to be an utter failure for 

 fluids. 



Alcohol dissolves out the brown tannin in cork, and 

 the specimens usually absorb the tannin, and turn to 

 a brownish colour. If the specimens are wanted for 

 histological m work, corks should be avoided and glass 

 stoppers used. 



Bottles with Glass Stoppers. — For the permanent 

 storage of specimens a glass-stoppered bottle is not 

 to be surpassed. The small sizes — \ ounce (15 c.c.) to 

 4 ounces (120 c.c.) — are most suitable for general use, 

 and when larger sizes are required it is much cheaper 

 to select a good glass-capped fruit-jar. 



Glass-stoppered bottles vary considerably in quality 

 and in price. The cheap ones have rather coarsely 

 ground stoppers, not always fitting accurately in the 

 neck of the bottle. The best quality have very 

 smooth-ground stoppers, each ground to its bottle ; 

 they fit accurately, and are usually numbered. 



Everyone who has had any experience with glass- 

 stoppered bottles sooner or later finds out that even 

 the best quality bottle is not absolutely proof against 

 the evaporation of alcohol. To prevent evaporation 

 the stopper is often coated with vaseline or lard. The 

 disadvantage of vaseline is that it becomes too liquid 

 in warm weather, and it gradually works its way down 

 the stopper and drops into the fluid, forming a harm- 

 less oil globule in alcohol, and an oily scum over 

 formalin. Lard, on the contrary, slowly loses its 



