If the given mass, enclosed as before, is divided into two parts, each of which is homogeneous and ﬂuid, by a diaphragm which is capable of supporting an excess of pressure on either side, and is permeable to some of the components and impermeable to others, we shall have the equations of conditions
δη′ + δη′′ = 0, δν′ = 0, δν′′ = 0
and for the components which cannot pass by the diaphragm
δm′a = 0, δm ′′ a = 0, δm
′ b = 0, δm
′′ b = 0, etc.