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constructed air thermometer (figured and described), the authors have found that the expansion of mercury from its freezing point to 0° C. is quite uniform; and that there is no critical point as in the case of water. Very great contraction, however, takes place when mercury passes from the liquid to the solid state.

Сн. В.

Heats of Formation of Potassium Alkyl Oxides. By DE FORCRAND (Compt. rend., 104, 68-71).-Potassium propyl oxide, C2H,OK, is obtained from normal propyl alcohol in the same way as the methoxide and ethoxide. Heat of solution at 12-15° = +14·92 cal.

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Potassium isobutyl oxide, CH,OK, is obtained from fermentation isobutyl alcohol in a similar manner, and alters very rapidly when exposed to air. Heat of solution +17·16 cal. The thermal disturbances resulting from the reactions corresponding with those given in the case of the preceding compound are +20-15 cal.; -0.34 cal.; +1.76 cal.; +33.53 cal.; and +8.89 cal. respectively.

Potassium amyl oxide, CHOK, forms white, silky crystals, which alter rapidly when exposed to air. It was prepared from fermentation amyl alcohol. Heat of solution +13.98 cal. The thermal disturbances corresponding with the five reactions given above are +23 27 cal.; +278 cal.; -1.35 cal.; +36·65 cal.; +859 cal.

The values obtained with these three compounds agree closely with those previously obtained with the methyl and ethyl derivatives. The differences are greatest in the case of the heats of solution of the solid compound in an excess of the corresponding alcohol, and these differences indicate a greater or less degree of dissociation of the polyalcoholic alcoholates.

The following table shows the heats of formation of these compounds from their elements. The values agree closely except in the case of the last two compounds, which, however, are not derived from normal primary alcohols :

K solid + H gas + O gas = HOK solid.. develops + 104.32 cal. K solid+C (diamond) + H, gas + O gas CH2OK solid

K solid + C (diamond) + H, gas + O gas = C2H2OK solid...

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+ 100-11

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+ 106.18

K solid+C3 (diamond) + H, gas + O gas =C,H,OK solid...

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Heat of Formation of Sodium Alkyl Oxides. By DE FORCRAND (Compt. rend., 104, 169-172).-Sodium propyl oxide is obtained in white, deliquescent crystals by dissolving sodium in propyl alcohol and heating the product at 200° in a current of dry hydrogen. Heat of solution +13:50 cal. A solution of the metal in excess of propyl alcohol, when allowed to evaporate in dry air, deposits crystals of the compound PrONa + 2PrOH, analogous to the compounds obtained under similar conditions with the methoxide and ethoxide.


Sodium isobutyl oxide is obtained in a similar manner in white, deliquescent crystals, which alter slightly in dry air. Heat of solution at +10° 14:25 cal. If sodium is dissolved to saturation in isobutyl alcohol at 150° and the liquid allowed to cool, it deposits crystals of the trialcoholate, C,H,ONa + 3C,H,OH. The heat of solution of this compound is +17-31 cal., and hence

CH,ONa solid + 3C,H,OH liq. = C.H,ONa,3C,H,OH solid

develops +5.56 cal.

Sodium amyl oxide, prepared in a similar manner, alters when exposed to dry air, although not to the same extent as the potassium compounds. Heat of solution = +14.21 cal. An alcoholate, CHONa+ 2CH1OH, can be obtained in crystals.


The table contains the thermal disturbances corresponding with the following five reactions, and the last column gives the heats of formations of the solid compounds from the solid and gaseous elements. The corresponding values for the hydroxide, methoxide, and ethoxide are also given :—

(1.) ROH liq. + Na2O solid = RONa solid + H2O solid. (2.) ROH liq. + NaHO solid = RONa solid + H2O solid.


(3.) RONa solid + H2O liq.

(4.) ROH liq. + Na solid

= ROH liq. + NaHO solid. = RONa solid + H gas. (5.) RONa solid + nROH liq. = RONa diss. in nROH liq.

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The variations in the values are similar to those previously observed in the case of the corresponding potassium compounds.

C. H. B.

Potassium Glyceroxide. By DE FORCRAND (Compt. rend., 104, 116-118).-92 parts of glycerol are added to a concentrated solution of 391 parts of potassium in absolute ethyl alcohol. Combination takes place rapidly, and the compound C,H,KO,,EtOH separates in transparent lamellæ, which seem to belong to the orthorhombic or monoclinic system. A further quantity of the crystals can be obtained by concentrating the mother-liquor; they are rapidly decomposed by moist air.

The heat of solution of the compound in water is -0.06 cal. C3H2O, liq. + KOH solid + EtOH liq. = H2O solid + С¿H‚О ̧K,EtOH solid, develops +18:53 cal.

When heated at 120° in a current of dry hydrogen, the crystals lose alcohol and yield the glyceroxide C3H,O,K. The heat of solution of this compound at +15° is +0·18 cal.

CHO, liq. + KHO solid = C,H,O,K solid

+ H2O solid ...

C3H7O3K sol. + EtHO liq. =C3H,O,K,EtOH solid

CHO, liq. + K2O solid = C2H2O2K solid + H2O solid...

CH.б, liq. + K solid = C2H,O,K solid +

develops + 15.84 cal.

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+ 49.71

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H gas The last value is higher than that obtained in the case of the sodium compound, and approaches the corresponding value for phenol.



CHO, liq. EtOK diss. in nEtHO liq. CзH,O,K,EtOH diss. in nEtOH liq. develops + 317 cal. The direct formation of the simple glyceroxide would likewise be exothermic, but the development of heat (+046 cal.) would not be so great.

The values for potassium glyceroxide and its alcoholate are higher than those for the sodium compounds, except in the case of the heat developed by the union of the glyceroxide with the alcohol. This last result agrees with the fact that the alcoholate of potassium glyceroxide rapidly loses alcohol over sulphuric acid, whilst the sodium compound does not alter. The heats of formation of the two

compounds from their elements are

C3 (diamond)+ H, gas + O, gas + Na solid
CH,O,Na solid


C3 (diamond) + H, gas + 03 gas + K solid =CH,O,K solid....

develops +209-42 cal.

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Thermal Properties of Ether. By W. RAMSAY and S. YOUNG (Proc. Roy. Soc., 40, 381-382).-In continuation of experiments on the physical constants of ethyl alcohol, the authors have made a similar study of ether, and numerical values have been obtained for the expansion of this liquid, the pressure of its vapour, and its compressibility in the gaseous and liquid states. From these results, the

densities of the saturated vapour and the heats of vaporisation have been deduced; the range of temperature of the observations is from -18° to 223°. The saturated vapour of ether, like that of alcohol, has an abnormal density, increasing with rise of temperature and corresponding rise of pressure. The critical temperature of ether seems to be 1940, the critical pressure 35-61 atmospheres; the volume occupied by 1 gram of the substance at 184° is 36 to 4 c.c. V. H. V.

Vapour-tension of Water from Salt Solutions. By W. W. J. NICOL (Phil. Mag., 22, 502-516). In 1835, Legrand (Ann. Chim. Phys., 59, 423) examined the effect of various salts in solution on the boiling point of water, and found that salts might be divided into those for which the quantity of salt necessary to produce a rise of one-half degree diminishes with the concentration (NaCl, KCl, &c.); those for which this quantity is fixed (KClO3); those for which it increases with the concentration (NaNO3, KNO3, &c.); those for which it first diminishes, then is constant for a few degrees, and finally increases rapidly up to the point of saturation. The last was the most general case.

Legrand's results were incomplete and defective, in so far that the temperature was variable. Wüllner's experiments (Ann. Phys. Chem., 110, 564) have added little to the subject. In the author's experiments, the temperature was kept constant, and the tension of the vapour observed. Four salts, NaCl, KCl, NaNO3, and KNO3, which crystallise without water, were examined as follows: From 2 to 25 molecular proportions of the salt were dissolved in 100 molecular proportions of water, and the solution heated to boiling under diminished pressure in a flask provided with a condenser, and containing a large quantity of zinc to prevent superheating. pressure was then allowed to rise slowly until the boiling point, measured by a thermometer with its bulb completely immersed in the liquid, rose to 70°. At intervals of 5° from 70° to 95°, the pressure was observed, and the difference between this pressure, p', and the vapour-tension of pure water, p, at the same temperature, also measured by a submerged thermometer, showed the "restraining effect" of n molecules of the salt. The quantity P-P



was the restraining effect for each molecule at the particular temperature. Tables of these values for the various temperatures are given, and from these the following conclusions may be drawn.

The restraining effect of each salt molecule increases with the concentration in the case of sodium chloride, and less markedly so in the case of potassium chloride. For sodium nitrate, it diminishes as concentration increases, and still more so for potassium nitrate.

Rise of temperature diminishes the restraining effect of sodium. chloride, leaves that of potassium chloride unaffected, increases that of sodium nitrate, and still more increases that of potassium nitrate.

When both temperature and concentration increase, the salts form the same series; that is, there is diminution of the restraining effect of sodium chloride, less of that of potassium chloride, little or none of that of sodium nitrate, but marked increase of that of potassium nitrate.

When the solubility as a function of the temperature is considered, the same order is preserved. That of sodium chloride increases slightly with the temperature; that of potassium chloride rather more; that of sodium nitrate to a still greater extent; whilst that of potassium nitrate increases enormously.

There is clearly a connection between increase of solubility and restraining effect.

Some of these results are directly opposed to those obtained by Wüllner, who found that the total effect was in all cases in direct proportion to the amount of salt dissolved; but they agree satisfactorily with those of Tammann (Abstr., 1885, 862), with which the author compares them.

The author points out that these results are in accordance with his theory of solution (Abstr., 1884, 253). According to this, solution results from the tendency towards equilibrium of three forces, attraction of water for water, and of salt for salt (cohesions), and attraction of salt for water (adhesion). These three forces may be unequally affected by rise of temperature; and accordingly as difference between adhesion and the sum of cohesions at any temperature is > = < the same difference at a lower temperature, so is solubility >=< solubility at a lower temperature. Now the restraining effect per molecule is seen from the tables to be nearly the same for the four salts in dilute solution; or, for n = 2, p P' for NaCl =

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= 3.75. In strong

4-25, for KCl = 3·8, for NaNO3 = 425, for KNO3 solutions it is very different. Now the heat of solution is as follows: NaCl = 1180, KCl = -4400, NaNO, 5200, KNO1 = - 8500; regarding this as a measure of the work done in effecting a change of state, it is evident that the cohesion of the salts increases from sodium chloride to potassium nitrate. It may reasonably be supposed that concentration has but little effect on the attraction for water of a salt having small cohesion; but that it slowly diminishes this attraction when the cohesion is large, until saturation is reached. The influence of concentration is thus accounted for.

With regard to the effect of rise of temperature, it is evident that all three forces will be thereby diminished. If the cohesions be diminished a little more than the adhesion, the salt will be more soluble, and its restraining effect diminished at the higher temperature. But if the cohesions be large, and largely diminished by rise of temperature, the comparative value of the adhesion will be increased, and increase of restraining effect will result. Сн. В.

Vapour-tension of Sodium Acetate. By H. LESCŒUR (Compt. rend., 104, 60-63).-Sodium acetate and water will furnish three distinct systems, the first of which is prepared at the ordinary temperature with the crystallised salt NaCH,O2 + 3H2O; the second with the fused and dehydrated salt; and the third by heating the two first systems to complete solution, and then cooling the liquids. Determinations of the maximum vapour-tensions of the three systems at 20° indicate the existence of at least three isomeric systems, but as soon as the quantity of water present becomes sufficient for complete

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