There is a diatomaceous earth mine just over the mountain from where I live in Northern California.Its at an elevation of about 3000 ft.The stuff is taken out of an open pit mine and processed by heating somehow then bagged.It is used for all kinds of filtering ,a lot being used for swimming pools.It has the appearence of walls of solid white chalk where roads have been cut through it.My kids used to break off chunks of it to mark off hop scotch squares. In my 1945 edition of ABC and XYZ it states:"It should be explained that the spores of AFB can stand boiling for 5 hours and in many cases retain their vitality to germinate and grow on culture media although under such long boiling they may lose their virulence...." --------------------------------------------- This message was sent using InterStar WebMail