66 INVERTEBRATE PALAEONTOLOGY 



ably a heavier white powder, over the surface. The 

 powder works its way into the narrow septal spaces, 

 while continued rubbing prevents its adhesion to the 

 chamber-walls. 



(V) STORAGE AND PRESERVATION 



Whether a collection of fossils is displayed in cases or 

 cabinets, or stored in boxes for occasional reference, the 

 one thing needful for its safety is cotton-wool. The 

 utmost care should be taken to keep specimens from 

 touching one another. The practice of fastening fossils 

 with glue to wood or card is to be deprecated. Speci- 

 mens thus stuck down cannot be properly handled for 

 study, while attempts to release them often lead to 

 disaster. Minute fossils, which may get lost in wool, can 

 be stored in glass tubes, in the bottoms of which felt has 

 been fastened. 



Most fossils, if protected from shock or attrition, may 

 be trusted to remain intact for indefinite periods. But 

 some, especially petrifactions in marcasite, soon disinte- 

 grate unless precautions are taken. The preservation of 

 pyritous fossils is one of the most difficult problems 

 associated with practical palaeontology. When exposed 

 to moisture, Marcasite rapidly decays into Sulphurous 

 acid and Ferrous sulphate ; disintegration is often 

 indicated by efflorescence of the latter. The change 

 depends on the presence of damp air, so that inclusion 

 of a little Calcium chloride or washing soda with the 

 specimen will retard decay, though it cannot prevent it 

 entirely. Small specimens can be preserved in petrol or 

 similar oils, but this is usually inconvenient. Marcasite 

 fossils can only be maintained in good condition by 

 frequent examination. At the first sign of decay the 

 specimen should be soaked in a solution of caustic 



