var dolar_kitco = "$ 12.96"; 
var oro_kilo = "$ 516,940.00"; 
var plata_kilo = "$ 8,152.13"; 
var oro_onza = "$ 1,241.50"; 
var oro_gramo = "$ 516.94"; 
var plata_onza = "$ 253.53"; 
callback_Metal();