Equivalent, Thermo-chemical

The calories evolved by the combination of one gram of any substance with its equivalent of another substance being determined, the product obtained by multiplying this number by the equivalent (atomic or molecular weight / valency) of the first element or substance is the thermo-chemical equivalent. If expre ed in kilogram calories, the product of the thermo-chemical equivalent by 0.43 gives the voltage required to effect such decomposition. The following are thermo-chemical equivalents of a few combinations: Water 34.5   Zinc oxide           43.2   Iron protoxide       34.5   Iron Sesquioxide     31.9 X 3   Copper oxide         19.2