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The density of a variety of alcohols has been measured over ranges of temperature below and above the boiling point. It is shown that the variation of orthobaric density difference with temperature may be represented fairly well by the Verschaffelt equation. In general the exponent of the equation is substantially lower than that found for normal liquids, and its value depends on the temperature range examined.

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The density o.f a series of diphatic mines together with that of aniline and its methyl denivatives has been measured over ranges of temperature below and above the normal boiling point. The variation of arthabark density difference may be represented by equations crf the Verschaffelt type usinlg estimated vailues of the critical teanperature. 011 this h i s it is found that rhe exponent for Be lower members is sltghtly higher than that for non-associated liquids and that its value decreases with increasing complexity of the annine. In general, the exponent for secondary amines is lower than that for primary amines. and the still lower values for tertiary amines Is to be ascribed to causes other b a n hydrogen :bonding. The behaviour of aniline and i,ts "-methyl derivatives is well represented by the Verschaffelt eqcation over a range of 300".It is shown that the Lewis equation relating to zero and critical densities is obeyed closely by assodated substances.Introduction.

The temperature variation of density, vapour pressure, and surface tension of the liquids have been measured, and the molecular volume, latent heat of vaporisation, and Kleeman-Macleod constants have been determined. The invariability of the latter constants over a wide range of temperature shows that the compounds behave as normal liquids.The solid-liquid equilibria of binary systems of the compounds have been examined, and it is shown that the type of equilibrium may be related t o the difference between the parachors of the components.In an examination of the isosterism of the CH group with the atoms of the elements of Group VB, i t is concluded that factors other than the weight of the groups are involved in isomorphism. The equilibria between tetraphenyltin and each of the triphenyl compounds have been determined, and earlier measurements have been corrected.No systematic study of the physical properties of liquid triphenyl compounds of the elements of Group VB has hitherto been made, although a few measurements of the density and surface tension over limited ranges of temperature have been carried out by Pascal (Compt. rend., 1913(Compt. rend., , 156, 1905 and by Walden and Swinne (2. physikal. Chem., 1912, 79, 713), respectively. In the present work it is found that the variation of density with temperature is normal for a range of 200' above the m. p., but triphenylbismuthine begins to decompose a t 180°. It will be evident from the data in Table I that Pascal's values of the molecular volumes, VsOo, of the solid are less regular than the estimated molecular volumes, V,, of the liquid a t the boiling point. If Kopp's values (Annalen, 1855, 96, 153) are taken for the atomic volumes of carbon (11.0) and hydrogen (5.5), the approximate atomic volumes of the elements of Group VB in this type of compound are : N, 16.5 ; P, 29.5; As, 34.5 ; Sb, 40.5.The atomic parachors given by Sugden (op. cit.) are : N, 12.5; P, 37.7 ; As, 50.1 ; Sb, 66.0; Bi, 80.