For decades, the Cailletet-Mathias (CM) law of rectilinear diameter was the base for determining the critical density for gas liquid-liquid critical point or the critical consolute concentration in mixtures of limited miscibility. Almost four decades ago, the decisive evidence showing the critical anomaly of the binodal's diameter questioned the CM law reliability.

This report presents the new method, fast & simple in use, to determine the coexistence curve (binodal) and the critical concentration. Notable is the experimental simplicity of the method: for the preliminary estimation it is enough to prepare two samples with different total concentrations or densities and observed relative volumes occupied by coexisting phases (or fractional meniscus heights) for two different temperatures. The method is illustrated basing on experimental studies in nitrobenzene – hexane mixtures of limited miscibility. Notable is the importance of this result for a variety of practical implementations, ranging from chemical physics to foods and pharmaceuticals technologies. Additionally, the manifestations of various stages of the critical opalescence, from dark-navy-blue to bluish and whitish, in the broad range of temperatures and concentrations, are shown and discussed.

数十年来，Cailletet-Mathias（CM）的直线直径定律是确定气液-液临界点的临界密度或混溶性有限的混合物中的临界溶质浓度的基础。大约四十年前，决定性的证据显示了双脚架直径的严重异常，这对CM法则的可靠性提出了质疑。

本报告介绍了一种新的方法，该方法使用简便，快速，可以确定共存曲线（双曲线）和临界浓度。值得注意的是该方法的实验简便性：对于初步估计而言，准备两个具有不同总浓度或密度以及观察到的在两个不同温度下共存相（或半月形弯液面高度）所占据的相对体积的两个样品就足够了。在有限混溶性的硝基苯-己烷混合物的实验研究的基础上说明了该方法。值得注意的是，此结果对于从化学物理到食品和制药技术的各种实际实现非常重要。此外，从乳白色到深蓝色到蓝色和白色，关键乳白色的各个阶段的表现，