Scratch hardness Scratch hardness Scratch hardness tests are used to determine the hardness of a material to scratches and abrasion. The earliest test was developed by mineralogist Friedrich Mohs in 1820 (see Mohs scale). It is based on relative scratch hardness, with talc assigned a value of 1 and diamond assigned a value of 10. Mohs' scale had two limitations; it was not linear, and most modern abrasives fall between 9 and 10. Raymond R. Ridgway, a research engineer at the Norton Company, modified the Mohs scale by giving garnet a hardness of 10 and diamond a hardness of 15. Charles E.
On the Rocks (play) there is nothing new in this, since the "extermination of what the exterminators call inferior races is as old as history." What is new is that modern politicians since the French revolution have created a social principle of extermination, whether it be of aristocrats as in the case of France, or Jews as in Germany. This is an outgrowth of class conflict, but in the future such decisions can be made scientifically. On the Rocks (play) On the Rocks: A political Comedy (1932) is a play by George Bernard Shaw which deals with the social crisis of the Great Depression.