[25] COLLECTING AND PREPARING FOSSILS — SCHUCHERT. 



All of the marks left by cutting- tools should be removed. The white 

 scratches can all, be removed with very dilute muriatic acid and brush- 

 ing, but be careful that the acid is not strong, otherwise calcareous 

 fossils will take on a gloss which is objectionable. 



The best way to trim slabs is to cut them with thin, tin circular saws 

 edged with diamond dust, operated by either foot or steam power, or by 

 breaking between two sharp-edged jaws, the upper one of which is made 



to descend by whirl- 



ing a large wheel 

 working on a slow 

 gradient screw. A 

 number of forms of 

 pincers and cutting 

 tools are used in cut- 

 ting and trimming fig. 5.-Wire brush. 



specimens. The more important of these are here reproduced (see figs. 

 6-12). Small hammers are useful, but great care must be taken to pre- 

 vent shattering or breaking the fossil. 



Broken fossils, if small, are best mended with fish glue; when large 

 enough plaster of paris should be added to give the glue greater body. 

 Sand bags are very serviceable in working slabs and large fossils, 

 particularly when chisels and hammers are to be used. In remov- 

 ing rock from skeletons, 

 sand bags are of the 

 greatest service to block 

 up and remove pressure 

 from weak spots or to 

 ease strains when turn- 

 ing specimens. 



Cleaning with acids and 

 j>otos/i.— Calcareousrocks 

 with siliceous fossils can 

 be etclied in a solution of 

 about one part of com- 

 mercial muriatic acid to 

 two parts of water. Use 

 dishes of various sizes 

 and set these out in the 

 air, otherwise the escap- 

 ing fumes will corrode all metallic surfaces in the room. Once or twice 

 each day the rock can be subjected to fresh dilute acid, but first wash 

 away the dead acid under a stream of running water. Also transfer 

 the loose material at the bottom of the dish to another with clear 

 water, in Avhich it is best to leave the material for a few days to soak 

 out all of the acid, otherwise your fossils may always have a wet and 

 greasy appearance. A very little caustic potash added to the water 



Fig. 6. 



Fig. 7. 



Cutting forceps. 



