differential thermal analysis (DTA)  differential thermal
analysis (DTA), in analytical chemistry, a technique for
identifying and quantitatively analyzing the chemical
composition of substances by observing the thermal behaviour of
a sample as it is heated. The technique is based on the fact
that as a substance is heated, it undergoes reactions and phase
changes that involve absorption or emission of heat. In DTA the
temperature of the test material is measured relative to that of
an adjacent inert material. A thermocouple imbedded in the test
piece and another in the inert material are connected so that
any differential temperatures generated during the heating cycle
are graphically recorded as a series of peaks on a moving chart.
The amount of heat involved and temperature at which these
changes take place are characteristic of individual elements or
compounds; identification of a substance, therefore, is
accomplished by comparing DTA curves obtained from the unknown
with those of known elements or compoun