470 Intelligence and Miscellaneous Articles. 



shaped vessels. If we take a glass box with parallel sides which 

 are at a distance of a centimetre apart, it is seen that the inert 

 space presents itself as a surface curved in the opposite direction to 

 the meniscus. It can moreover be observed that at the positions of 

 greatest curvature, a gradual equalization or a fresh reaction-zone 

 is formed. If a horizontal glass cylinder closed by parallel glass 

 plates is taken, the curvature of the active space is seen in great 

 sharpness and beauty. 



If the reaction takes place between two glass plates which are 

 inclined to each other at an acute angle so that their line of contact 

 is vertical, the height of the meniscus is represented by a deeper 

 position of the inert space. 



In capillary tubes which, after being filled, are placed horizontally, 

 the inert space is met with on each side. Even if the capillary 

 tubes are taken so fine, that the lumen must be examined by a 

 magnify ing-power of 300 times, the active and the inert space can 

 be separately observed. The reaction occurs with separation of 

 small molecular drops of chloroform in the middle of the liquid 

 cylinder, while it remains clear at each end. With very small 

 drops in capillary tubes there is no reaction *. 



If tubes closed at the top are filled with the active mixture so 

 that there is no air-bubble, the decomposition is uniform throughout 

 the entire liquid. If, however, tubes open at the top are filled with 

 the liquid, and are closed by a small transparent animal membrane 

 stretched in a lead frame, it is possible by carefully raising it to 

 show here also the inert space. 



If a glass tube open at both ends is placed on a fine membrane, 

 and is closed at the top also by a membrane, it is seen that when 

 the tube is held vertically an inactive space can be observed below, 

 in which the chloroform gradually settles as a cloud. I have not 

 been able to ascertain whether the reaction in this case is also 

 limited at the sides of the tube. 



If a specimen of the liquid be taken from the inert space by 

 means of a capillary tube, and it be warmed, decomposition at once 

 sets in. This is a proof that the two substances contain unaltered 

 hydrate of chloral and sodium carbonate. It is of course im- 

 portant to observe the phenomena of the inert space by other 

 reactions which take place slowly. The reaction which takes 

 place between iodic and sulphurous acids according to the following 

 equations : 



3S0 2 + HI0 3 = 3S0 3 + IH 



5IH +HI0 3 =3H 2 + 6I 



was found to be particularly suitable, since it has been found by 



Landoltf that by suitable dilution, and variation of the quantities, 



it can be delayed at pleasure and in accordance with a definite law. 



The occurrence of the iodine reaction is made manifest by the 



* For this experiment it is necessary to free the liquid from absorbed 

 air by boiling. 



t Berliner Sitzungsberichte, 1885, xvi., and 1886, x. 



