The Experimental Production of the Phenomena Distinctive of Virtified Forts
Early Thirteenth Century
The term vitrified is applied to those forts in Scotland or abroad that comprise within their ramparts broken stones fused together to form a solid mass. The extent of such vitrifaction varies enormously from site to site. The idea that the combustion of the walls would generate a temperature between 800Â° C. and 1100Â° C. such as was necessary to melt the stones employed at Rahoy and Finavon was tested by experiment. An essential moment in the production of vitrifaction is the conversion of the wood into charcoal by a process of distillation in which heat is absorbed by the timbers. It is only after the completion of this endothermic reaction that the combustion of the resultant charcoal under suitable conditions of ventilation and in contact with the stones produces the high temperature needed to fuse the rocks.