**Abstract:** To clarify the controversy over Newton’s constant, G^{CODATA} = 6.673(10)x10^{-11}m^{3}kg^{-1}s^{-2} – offered e.g. through enlarging its uncertainty from 128 ppm to 1500 ppm in 1998 – the formula G_{AB} = ** G**(1-Δm

_{A}/A

**)**

*m*^{-1}(1-Δm

_{B}/B

**)**

*m*^{-1 }is presented for the gravitational force between two isotopes with the mass numbers A and B, containing a constant

**= 1.006727885(8) amu and a new defined mass defect Δm**

*m*_{A}= A

**-m**

*m*_{Isotope,A}. The formulae with the constant of nature

**and for Δm**

*G*_{A}emerge from the Unified Field consisting of the electromagnetic and of the covariant gravitational field with gravitational charges. The gravitational charge of the electron + proton system and of neutron

*g*is the same

_{n}*g*=

_{n}*g*with

**m**

*G**= g*/4. From available experiments with copper

^{2 }**= 6.576(6)x10**

*G*^{-11}m

^{3}kg

^{-1}s

^{-2}is determined. With

**and with the empirical known mass number dependent Δ**

*G*_{A}

^{MD}=Δm

_{A}/A

**, the new theory predicts aside of hydrogen: a composition dependent G**

*m*_{AB}in a range of ~ 0.7 % (observed is 0.74 %). The relative difference of inertial and gravitational mass of a body is 0.78 % and the Universality of Free Fall is violated in this order. A fall experiment with Li and Fe must directly show a measurable Δa/a 0.33%. The basic hypothesis of UFF was stated by Philoponus and Galileo Galilei and was taken over by Albert Einstein for the General Relativity Theory and for the gravity.

PACS Numbers: 04.20.Cv, 04.80.Cc, 06.20.Jr, 12.10.-g

Non-equivalence of inertial and gravitational mass