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At an ordinary zero-field continuous phase transition, the positive quartic coefficient remains nonzero while ${\mathcal{A}}_2\to 0$. Approaching from the ordered side therefore sends the variable $X$ in the tricritical crossover scaling form to $+\infty$, rather than to zero. With $Y=0$ the dimensionless minimizer obeys ${\psi }^4+X{\psi }^2-1=0$, soAt that stationary point, substitution gives ${\Phi }_{-}(X,0)=-{\psi }^2/4-{\psi }^6/12$. Its large-quartic asymptotic of tricritical scaling is consequently ${\Phi }_{-}(X,0)\sim -1/(4X)$, andIf ${\mathcal{A}}_2$ crosses zero linearly with temperature, this is quadratic in $T-T_c$, giving a finite heat capacity jump rather than a power divergence. ThereforeFor locally constant ${\mathcal{A}}_4>0$ and slope $a={\partial }_T{\mathcal{A}}_2{|}_{T_c}$, the leading singular heat capacity jump from this term is $\Delta C=T_c{a}^2/(2{\mathcal{A}}_4)$. Treating $\Phi$ as a nonzero constant while $X\to \infty$ would incorrectly assign the tricritical exponent to this ordinary transition.