8 14 NORTH AMERICAN INDEX FOSSILS. 



a hardening fluid. The commercial product requires thinning by 

 water before it can be used. For the preservation of graptoHtes, 

 deHcate arthropods and similar fossils, Bather recommends " a thin 

 solution of cellulose, apparently in amyl acetate " which is sold 

 under the name of " Zapon " for the preservation of antiquities.^ 

 It " forms an almost imperceptible lacquer which prevents the 

 action of the atmosphere. It has also the effect of intensifying the 

 colors and outlines of dark fossils such as graptolites. The vapor 

 is inflammable and if used in a closed room produces headaches." 



Fossils which have been changed to pyrite or marcasite are very 

 prone to disintegrate, especially the latter. These fossils may be 

 kept in petroleum or benzine or in a solution of carbon tetrachloride. 

 The stopper of the bottle should be glass. 



For dry preservation the following method has been proposed: 

 After careful cleaning, the fossil " should be placed for some 

 hours in a hot solution of caustic alkali ; this neutralizes all the free 

 acid without attacking either the pyrites or any carbonate of lime 

 that may be present. Should a white coating be produced, it may 

 be removed by dilute hydrochloric acid', but after this the specimens 

 should be very carefully washed with distilled water. They must 

 then be dried, preferably by passing through alcohol or petrol, 

 according to the treatment eventually selected. 



" If passed through the alcohol, when all the water has been 

 driven off, the fossil may be placed in a thin solution of shellac and 

 left in it for some time, so as to allow the shellac to penetrate as 

 far as possible. A stronger solution of shellac may be applied as 

 a final coating. If passed through the petrol, the fossil may be 

 placed directly in melted paraffin wax and left therein a sufficient 

 time for the wax to be absorbed."^ Bichromate of potash has been 

 recommended according to L. Abbott in place of caustic alkali. 

 Zapon has also been used by Bather as a protective varnish. 



4. Making of Artificial Casts from Natural Molds. 

 In many cases the fossil has been removed in one way or 

 another, and nothing but the mold remains. In such cases a cast 

 made with gutta-percha will often give the surface features of the 



* Supplied by the British Xylonite Co. as " F. 10432 " — 9s. 8d. per gallon. 

 ^ Bather, F. A., he. cit., pp. 88-89. 



