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Saturation of Arsenic Acid with Calcium and Strontium Oxides. By C. BLAREZ (Compt. rend., 103, 639-640).—The heat developed by the saturation of a normal solution of arsenic acid by means of calcium or strontium oxide in aqueous solution is given in the following table :

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Neutralisation with the first equivalent is distinctly indicated by cochineal, but less distinctly by methyl-orange, and neutralisation with the second equivalent is indicated fairly well by phenolphthaleïn. The arsenate precipitated on addition of three equivalents of base is somewhat variable in composition, but approximates to the tribasic salt. With four and five equivalents, the precipitated arsenate is somewhat basic. The much greater tendency of calcium and strontium arsenates to dissociate in presence of water, distinguishes them from the corresponding phosphates. C. H. B.

Sodium Glycerolate. By DE FORCRAND (Compt. rend., 103, 596– 599). Sodium glycerolate, Č,H,NaO,, was prepared by Lett's method (Ber., 5, 159). Heat of solution at 16°, C,H,NaO,,C2HO, 1·08 cal.; C1H,NaOз, +1:07. From these values, and the heat of solution and neutralisation of glycerol, and the heat of solution of alcohol as determined by Berthelot, it follows that

CH(OH), liq. + NaHO solid + CHO liq.
= H2O solid + C,H,NaO, solid...
C3H,O, liq. + NaHO solid = C ̧H-NaO, solid
+ H2O solid..

and hence

develops +16·60 cal.

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+ 12.02

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CH,NaO, solid + C2HO liq. =

CH,NaO3, C2H.O solid....

+ 4.58

This result confirms the view that the substitution of sodium takes place in the glycerol and not in the ethyl alcohol.

C3H,O, liq. Na solid = C,H,NaO, solid +

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3.92,,

C3H,O3 liq. + C2H,NaO diss. in nC2H2O liq. =
CH,NaO3, C2H.O solid, ppt. in nCH.O liq.
This result shows that the formation of C3H,NaO,,C,H,O is

exothermic, whilst the precipitation of C,H,NaO, alone would be endothermic.

The alkaline glycerolates possess a somewhat general property of uniting with one molecule of monohydric alcohols to form crystallisable compounds. The thermochemical data show that polyhydric alcohols yield more stable derivatives than monohydric alcohols.

C. H. B. Heat of Evaporation of Homologous Carbon-compounds. By R. SCHIFF (Annalen, 234, 338-350).-The author uses an apparatus partly constructed of silver, which is so arranged as to prevent the vapour of the boiling liquid being superheated, and also to ensure the dryness of the vapour before it enters the calorimeter, two points to which sufficient attention has not been directed in the different forms of apparatus used by Berthelot (Mécanique Chimique, 1, 289), Brix (Ann. Chim. Phys., 55), and Depretz (Ann. Chim. Phys., 24, 323).

The author's tabulated results show that the heat of evaporation decreases as the molecular weight increases. In the case of isomerides, the substance with the lowest boiling point has the lowest heat of evaporation. The results confirm Trouton's statement that the molecular heats of evaporation are proportional to the absolute temperature at which the evaporation takes place (Phil. Mag. [5], 18, 84). The coefficient of expansion at 0° is inversely proportional to the absolute temperature of the boiling point under the normal pressure. W. C. W.

Development of Heat when Powders are Moistened. By F. MEISSNER (Ann. Phys. Chem. [2], 29, 114—131).—The author uses two experimental methods, a thermometric and a calorimetric. In the first, weighed quantities of the carefully dried powder and of water are brought together in a small glass vessel, their temperature having been carefully noted before mixing. The rise in temperature produced is recorded from time to time by a delicate thermometer immersed in the mixture. The second set of experiments were conducted in a Bunsen's calorimeter. The substances experimented on were ignited silica, "magnesia alba," glass powder, emery and animal charcoal with water, benzene, amyl alcohol, and glycerol.

For water and silica, the author finds a rise in temperature of 3·8— 45° C., with initial temperatures ranging from 0-19°; this result is contrary to that of Jungk (Ann. Phys. Chem., 125, 292), who states that with initial temperatures below 4° there is absorption of heat.

The author considers that the development of heat is due to the expansion of the colloïd when moistened, or that potential molecular energy is converted into heat. H. K. T.

Determination of the Specific Gravity of Soluble Substances. By L. ZEHNDER (Ann. Phys. Chem. [2], 29, 249–263).— In this paper, a simple method for the determination of the specific gravity of soluble substances is described, by means of which results accurate to the one-thousandth part can be readily obtained. The principle of it is as follows:-The substance to be determined is weighed

in the pyknometer, and the latter is then placed in an inverted position under water, so that the solid substance falls out, the air from the pyknometer being at the same time collected by a funnel provided with a bent tube, and completely filled with water; from this funnel the air is retransferred to the pyknometer, which is then again weighed; thus is obtained the weight of a volume of water equal to that occupied by the weight of the substance taken, which relation gives directly the specific gravity. To collect the displaced air, the pyknometer is inverted under a funnel provided with a delivery-tube, twice bent, and ending in a capillary opening, by means of which the air is again decanted into the pyknometer.

This method requires the following determinations: the weight of the substance whose sp. gr. is to be determined, the weight of the water replaced by it, and the capacity of the pyknometer; the difference between them is the volume of air; this is corrected for differences of temperature and pressure during the determination, and the corrected volume of air subtracted from the capacity of the pyknometer gives the corrected volume occupied by the substance; on dividing the weight of the substance by the latter value, the specific gravity is obtained. The special precautions to be adopted are discussed in full, and determinations are given of common salt and sugar candy, the results of which are fairly satisfactory. V. H. V.

Tension of Dissociation of Ammonium Hydrogen Carbonate. By BERTHELOT and ANDRÉ (Compt. rend., 103, 665-671).—The decomposition of ammonium hydrogen carbonate by water increases only very slightly with an increase in the proportion of water, and the maximum change is not effected until after a considerable lapse of time. The heat of dissolution of 1 gram-mol. in 25 litres of water is 6.85 cal.; whilst the heat of dissolution in 6-8 litres is · 6.2 cal.

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Perfectly dry ammonium hydrogen carbonate has no sensible tension of dissociation at ordinary temperatures in presence of air, ammonia, or carbonic anhydride, under a pressure of two-thirds of an atmosphere. Even when a current of these gases is passed over the salt, the evidence of any dissociation is extremely slight. That the salt does, however, possess a distinct, though extremely small, vapourtension, is shown by the fact that if it is left in a closed space over sulphuric acid, the latter increases in weight, and crystals of ammonium hydrogen sulphate form on the edge of the dish containing it.

These results are materially affected by the presence of very small quantities of water. If the water is entirely in the state of vapour, it exerts but little influence on the vapour-tension of the salt, but the effect is much greater in presence of liquid water, and if the salt is placed in a closed space in which there is also a vessel containing water, the latter increases in weight owing to absorption of ammonia.

The three constituents of the salt do not play the same part in its dissociation. Carbonic anhydride and ammonia are without influence on its vapour-tension at the ordinary temperature, whilst water determines its decomposition independently of the ordinary laws of dissociation. C. H. B.

Decomposition of Ammonium Hydrogen Carbonate by Water and Diffusion of the Ammonia through the Atmosphere. By BERTHELOT and ANDRÉ (Compt. rend., 103, 716-721). -A concentrated solution of ammonium carbonate, containing ammona and carbonic anhydride in the ratio 1: 185, was placed in a closed space, which also contained a vessel with a known weight of water. The atmosphere contained carbonic anhydride, but no appreciable quantity of ammonia. At first, the quantity of carbonic anhydride absorbed by the water in the second vessel was relatively greater than the quantity of ammonia, but after about eight days the distribution of ammonia and carbonic anhydride was uniform in both vessels. Similar results were obtained with dilute solutions, and it follows that pure water, in an atmosphere containing a small quantity of ammonia and a relatively much larger quantity of carbonic anhy. dride, tends to reform the acid carbonate, a result probably due to the fact that the carbonic anhydride, by reason of its greater insolubility, maintains a higher tension in the atmosphere. The diffusion. of ammonia from water to air in presence of carbonic anhydride does not take place in accordance with the same laws as the diffusion in the absence of any gas which can combine with the ammonia. The rate of diffusion of free ammonia from its aqueous solution into the air is very much more rapid than the diffusion of ammonia in combination with carbonic acid. The diffusion of free ammonia is accelerated by the presence of sulphuric acid, which absorbs the alkali from the atmosphere, but the presence of this acid has very little effect on the diffusion of ammonia from a solution of the carbonate, and the effect is less the more dilute the solution.

In presence of an excess of carbonic anhydride, the transference of ammonia through the atmosphere to an aqueous liquid takes place in a manner entirely different from the similar transference of ammonia in presence of an inert gas. The latter is conditioned by the tension of the ammonia in the solutions, whilst the former depends on the relative tensions of the carbonic anhydride in the liquids and the surrounding atmosphere. It is, in fact, the diffusion of the carbonic anhydride which regulates the decomposition of the ammonium hydrogen carbonate and the transference of the ammonia through the atmosphere. C. H. B.

Inorganic Chemistry.

Conversion of Calcium Hypochlorite into Calcium Chlorate. By G. LUNGE (J. Soc. Chem. Ind., 4, 722-724).—It has already been shown by the author that the reaction 6CaOCl, = 5CaCl2 + Ca(ClO3)2 does not take place completely and without considerable loss of oxygen, except in presence of an excess of chlorine, although that chlorine does not appear in the equation. The author's experiments point to the following conclusions:-The most

favourable way of converting hypochlorite into chlorate is to raise the temperature of the solution, and simultaneously have an excess of chlorine present therein. A large excess of chlorine is useless, perhaps injurious, for the yield of chlorate. On the large scale, it is not necessary to raise the temperature by artificial means, the heat produced by the reaction being sufficient to complete it. The conversion at the ordinary temperature proceeds almost at once to the limit of about 70 per cent., but subsequently makes very slow progress, so that it is impracticable to wait for its completion without heating.

D. B.

A Crystalline Silico-carbonate from Soda Liquors. By C. RAMMELSBERG (Chem. Ind., 9, 110-111).-Two specimens of crystals removed from the pump of a carbonating tower at the "Hermannia Chemical Works at Schönebeck had the following composition:—

13.28

COg SiO2. Al2O3. CaO. NaO. H2O.
I. 22.75 14.99 7.38
22.37 19.23 100
II. 21.50 15.00 8.03 12.41 21.66 21.40 100

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Allowing for adhering soda liquor, these numbers lead to the formula NaCa Al2(Si,C)21O63 + 30H2O, or the substance is a compound of the isomorphous normal carbonates and silicates

3[3Na2 (Si,C)O3, 2Ca (Si, C) O,],2A1(Si, C)3O18.

The crystals are rhombic, exhibiting the form of the primary pyramid with its acuter terminal edges truncated, or frequently a tabular form due to the development of the end face; the ratio of the axes is 0.5295: 1: 1·73.

These crystals were first observed in 1880, but the specimen then analysed contained an admixture of gay-lussite, and the silica and alumina were not recognised as essential constituents. M. J. S.

Sodium-calcium Carbonates from the Soda Manufacture. By C. REIDEMEISTER (Chem. Ind., 9, 111).—In the Chemische Industrie for 1884 the author described the rhombic crystals analysed by Rammelsberg (see preceding Abstract) as a hydrated sodium calcium carbonate. They are now found to occur in both the crude and carbonated liquors. In the former, in which formerly only gay-lussite had been recognised, they have now been observed with crystals of gay-lussite deposited on their surfaces. The gay-lussite crystals are chiefly deposited from liquors in process of cooling; the silicocarbonate from those undergoing slow evaporation. M. J. S.

Double Nitrites of Cæsium and of Rubidium. By T. ROSENBLADT (Ber., 19, 2531-2535).-The double nitrite of cæsium and cobalt, 3CSNO,Co(NO2)3 + H2O, is formed by boiling equal parts of cobalt nitrate and sodium acetate in water (15 parts), filtering, and adding to the cold solution first acetic acid (20 parts), and then a strong solution of sodium nitrite until the liquid has an orange colour, it is then filtered, and treated with a solution of a

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