This operation was necessitated by the fact that carbon dioxide has the power of breaking up the sulphur compounds formed by the lime, so that until all carbon dioxide is absorbed with the formation of calcium carbonate, the withdrawal of sulphuretted hydrogen cannot proceed, whilst since it is calcium sulphide formed by the absorption of sulphuretted hydrogen by the slaked lime that absorbs the vapour of carbon disulphide, purification from the latter can only be accomplished after the necessary calcium sulphide has been formed.
Silicon tetraiodide, Si14, is formed by passing iodine vapour mixed with carbon dioxide over strongly-heated silicon (C. Friedel, Comptes rendus, 1868, 67, p. 98); the iodo-compound condenses in the colder portion of the apparatus and is purified by shaking with carbon bisulphide and with mercury.
With open pans the vapour is free to diffuse itself into the atmosphere, and the evaporation is perhaps more rapid.
The vapour pressure-composition curve will now be concave to the axis of composition, the minima corresponding to the pure components.
Cadmium vapour decomposes water at a red heat, with liberation of hydrogen, and formation of the oxide of the metal.
Evaporation then continues at the constant temperature T, abstracting heat from the substance outside the refrigerator as shown by the line BC. The vapour is then compressed along the line CD to the temperature T2, when, by the action of the cooling water in the condenser, heat is abstracted at constant temperature and the vapour condensed along the line DA.
From 1865 onwards he treated this question in several papers, and in particular maintained the dissociation of vapour of chloral hydrate, in opposition to H.
We can calculate the heat of formation from its ions for any substance dissolved in a given liquid, from a knowledge of the temperature coefficient of ionization, by means of an application of the well-known thermodynamical process, which also gives the latent heat of evaporation of a liquid when the temperature coefficient of its vapour pressure is known.
This liquid, containing a large proportion of ammonia, gives off vapour at a low temperature, and therefore becomes a refrigerator abstracting heat from water or any surrounding body.
The vapour of chloroform when passed through a red-hot tube yields hexachlorbenzene C 6 C1 6, perchlorethane C,C1 6, and some perchlorethylene C 2 C1 4 (W.