Show purifying blackhead black Blac Kead lead for pencils Pen bils range proposes to purify poor black blade lead for pencils by digesting it in in a state of fine firl 0 powder for 36 13 hours fours in about twice its ita weight of stron strong 6 sul sulphuric pharic acid after chic about fo four 11 r parts of water to one of ac add 1 id should be added and aad the who aben leatto soak for balf an hour the acid should then be poured off and the lead washed when a pure black lead will be found at the te bottoni bottom of the vessel which should be of cassor gl assor stone ware vare the decanted sulphuric sul pharic acid contains contain iron and phate of alum I 1 i na runge also pro proposes to add a little lamp black to the lead so obtained in order to deepen the he tints of the lines drawn by a pencil made from it I 1 IV what hat are our oar elie chemists mist doin doing about a jet black pencil as a substitute tor for pen pea I 1 aud ad ink scientific american america n i |