30 THE POPULAR SCIENCE MOXTIILY
spread until the whole substance succumbs to the disease. Eesults of the tin pest are frequently found in museums. A tin vase in the British Museum which was found in Appleshaw, Hampshire County, England, and which dates back to 350 B.C. shows very strikingly the effects of the tin disease. The metal is not corroded, but it is dull in color and is so brittle that it can be broken with the fingers. Some of the fragments on being melted gave wliite tin with its original toughness and luster.
���FlU. lU. A TWO-IIU.NDHKD YEAU-OLD MEDAL THAT IS SUFrEKING
FROM THE Tin Disease.
Every one who has studied the advance of science during the last few centuries realizes tliat our modern inventions and processes of manufacture have been in many cases foresliadowed in the ancient world. Tlie use of gunpowder by tlie Chinese and thoir extraordinary success with glazes, as well as the perfection obtained by certain of the old civilizations in the use of cements, pigments, dyestuffs and in metal- lurgical processes, is familiar to every one. What tlie modern scientist discovers by painstaking investigation was learned in those days either by accident or as the result of centuries of experience. Consequently the fact that the tin disease was known in those days ought not to be surprising. Professor Colioii lias pointed to an observation of Aristotle.