The specific gravity of solids particles is defined as ratio of mass of given volume of solids to the mass of an equal volume of water at $4^0 C$.

The specific gravity is = G= $\dfrac{\rho_s}{\rho_w}$

The mass density of water $\rho_w$ at $4^0 C$ is one gm/m, 1000Kg/$m^3$

The specific gravity of solids for most natural soils fall in the general range of 2.65 to 2.80

Typical values for G

(1) Mass specific gravity $(G_m)$:- $\dfrac{ratio of mass density of soil}{mass density of water} = \dfrac{\rho_s}{\rho_w}$

obviously, the mass specific gravity of soil is much smaller than the value of specific gravity of solids.

(2) It is also known as appernt specific gravity or bulk specific gravity.

(3) Absolute specific gravity $(G_a)$:-

$G_a = \dfrac{(\rho_s)_a}{\rho_w}$