Indifferent Gas

II, 36, 1 is almost self explanatory two ground glass joints are used, but these may be replaced by rubber stoppers, if desired. The crude substance is placed in the flask A. Stopcocks 1 and 2 are closed, and the apparatus is exhausted through tap 3 the indifferent gas is then allowed to enter the apparatus to atmospheric pressure. The evacuation and filling with inert gas are repeated several times. The solvent is added through the tap funnel B. 

A. Naumann observed that the velocity of the dissociation of the solid and the recombination of the vapour is increased by increasing the surface area of the solid these velocities are proportionally smaller the nearer the observed press, is to the equilibrium value and the velocity of dissociation is greater the higher the temp. A. Horstmann has shown that the law of mass action describes the relation between the partial press, of ammonia and carbon dioxide, and that the dissociation press, is not perceptibly influenced by the presence of an indifferent gas—e.g. air—while the dissociation press, in the presence of one of the products of dissociation is smaller than in vacuo. In general, the total press, of the gases uniting to form a... 

Rhodium Arsenide, E.hAs2, has been prepared in a pure form by heating rhodium chloride with an excess of arsenic in an atmosphere of hydrogen.8 If finely divided rhodium is heated with excess of arsenic in an atmosphere of an indifferent gas, the arsenide produced is not pure.9... 

H. Rebs, and H. Schulze said that the tetritatrisulphide is also formed by heating the so-called tetritasulphide to about 100°, in an indifferent gas E. Dervin, by heating the hemitrisulphide or the octitahenasulphide with carbon disulphide in a sealed tube at 200° and A. Besson, by the action of phosphine on thionyl, sulphuryl, or pyrosulphuryl chloride. H. Giran s curve, Fig. 52, gives an idea of the part played by this compound in the binary system P-S. 

Sometimes the reaction continues until all the available chlorine has been consumed. With mass chains the reaction ceases when two chlorine atoms or two hydrogen atoms collide and form a molecule. With energetic chains, activated molecules are deactivated when colliding with the walls of the vessel or with an inert gas molecule. Increased reaction surface obtained e. g. by the presence of splinters, or an admixture of indifferent gas will reduce the reaction rate. 

Chemical Reactions.—P12H6 is dissociated when heated above 70° C-. in an indifferent gas—into its elements at 175° C. in CO 1 or into phosphorus and phosphine at 215° C. The ignition temperature in air is 120° to 150° C.1 The only liquids which dissolve it without decomposition are phosphorus and PaH4. It dissolves in ammonia at -40° C. with evolution of phosphine. After evaporation of the ammonia a black solid is left which appears to be an ammine of a higher hydrogen phosphide. Like the other phosphides it is easily oxidised by halogens, chlorates and nitric acid.2... 

The effect of surface tension on vapour pressure arises from the hydrostatic pressure 2aIr produced in the surface ( 11.VIIIG), and the vapour pressure over a plane surface should increase when the pressure on the liquid is increased, say by pumping an indifferent gas into a vessel containing liquid in equilibrium with its vapour.8 If the applied pressure dP is represented by 2a jr and substituted in (3), 15.VIII L ... 

Van Laar,2 ftom the basis flfi2=A/( i 2) ( 35.VTI C), deduced a complicated equation for the change of vapour pressure from po to Pi caused by the pressure p of an indifferent gas, and showed that it agreed vwith Bartlett s observation that the vapour pressure of water is increased to four times its normal value by a pressure of 1000 atm. of nitrogen. Van Laar s equation is ... 

Sublimations can also be conducted in crucibles, flasks, beakers, retorts, tubes, etc. The heating may be done in an air- or oil-bath. In order to lead off the vapours rapidly, a current of an indifferent-gas is sent through the apparatus. 

The vapour pressures of metals at high temperatures have been determined by the boiling-point method under various pressures of indifferent gas, by the effusion method ( 12.VIII J), and by other methods.5... 

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