Intelligence and Miscellaneous Articles. 469 



rents are produced in consequence of inequalities of temperature. 

 In the reduction of copper sulphate by grape-sugar, on heating, the 

 suboxide is first perceived in the upper part. We know also that 

 in reducing liquids which contain certain metallic salts, the products 

 of reduction are deposited on the surfaces opposed to them. It has 

 never, however, been observed that in liquids, perfect mixture 

 being presupposed, certain parts are withdrawn from the reaction, 

 or show some retardation in the change. 



I have succeeded in demonstrating the existence of a space in 

 mixtures in which a chemical reaction is not visible. 1 have called 

 it the inert space (todter Rauiri). In introducing this idea as the 

 result of my experiments, I would define it as that space in a 

 uniformly mixed liquid in which the reaction occurs either not at 

 all, or is retarded, or takes place to a less extent than in the 

 principal liquid. 



Reaction- space and inert space can be most sharply separa 

 from each other in the experiments which I adduce. The occurrence 

 of such an inert space is best demonstrated with hydrate of chloral, 

 which, when treated with sodium carbonate, decomposes into 

 chloroform, according to the following equation : 



C 2 C1 3 2 H 3 + Xa 2 C0 3 = CHCI3 + NaIIC0 2 + NaHC0 3 . 



With a suitable concentration, and mixture in proper equivalents, 

 the chloroform separates not in thick oily drops, but as a fine mist 

 which gradually collects in drops at the bottom. The reaction 

 does not start at once, but depends on concentration and tempera- 

 ture. The concentration proper for the observations can be so 

 arranged that the commencement of the reaction varies between 1 

 and 25 minutes. This time may even be considerably prolonged *. 



If the reaction is made in an ordinary test-tube, there is a space 

 of 1 to 3 mm. below the meniscus, which is not affected by the 

 reaction ; that is, it remains perfectly clear ; and the reaction-space 

 is bounded above with the sharpness of a hair, by a surface curved 

 in the opposite direction to that of the meniscus. 



The upper space in the liquid which thus remains clear is the 

 inert space in the hydrate-of-chloral reaction. 



Even after the tube has been left still for 24 hours this space is 

 visible ; for the boundary of the inert space can still be distinctly 

 recognized by minute spherules of chloroform which have not sunk. 

 If the test-tube is gently agitated, so that the chloroform-mist 

 passes into the inert space, after a few minutes the chloroform 

 settles to its former boundary, and the separation between the 

 inert space and the reaction-space is again reproduced. 



Careful observation showed that the clear layer of liquid was 

 diminished by the ascent of the chloroform-mist, and was not 

 increased by sinking. 



I have observed the inert space in this reaction in differently 



* I used equal volumes of aqueous solutions of 331 gr. hydrate of 

 chloral and 212 gr. sodium carbonate in the litre, which were diluted to 

 a corresponding extent, so as to prolong the duration of the reaction. 



