APPENDIX 



467 



TABLE XI. HARDNESS OF SUBSTANCES. 



We can compare the hardness of two bodies by rubbing them 

 together; the one having the greater hardness scratches or indents 

 the other. In the scale of hardness bodies usually have positions 

 between 1 and 10. The diamond is the only substance of hardness 

 10 (cf. 119). Substances that can be indented by the finger nail 

 have a hardness of less than 1 . A substance of hardness 6.5 is scratched 

 by a substance of hardness 7, but scratches a substance of hardness 6. 

 The list below is taken from the Smithsonian Tables, as they are given 

 in the "Handbook of Chemistry and Physics," published by the 

 Chemical Rubber Company, Cleveland, Ohio. 



