208 Mr Heycock, On a form of Apparatus [Nov. 24, 



This second equation in the notation of this paper is 



and is the second of the system of six formula? in § 13. 



(2) On a simplified form of Apparatus for determining the 

 density of Ozone. By C. T. Heycock, M.A., and F. H. Neville, 

 M.A. 



In 1868, M. Soret published in the Ann. Chim. Phys. t. 157 

 his researches on the density of ozone based upon its rate of 

 diffusion. 



The corrosive action and the instability of ozone led him to 

 devise a very complicated apparatus. The following is an account 

 of a much simplified form, for the same purpose, as used by the 

 authors. 



Their apparatus was made of two gas cylinders of thick glass 

 each containing about 300 cc, the mouths of the cylinders being 

 carefully ground. The closed ends of the cylinders were pierced 

 with a hole and each was fitted by an accurately ground tube and 

 stopcock. 



Care must be taken to grind the tubes to fit accurately the 

 holes in the cylinders as all lutes are unadvisable in the presence 

 of ozone. The mouth of each jar is closed by a thick sheet of 

 plate glass, which we call dampers, rather wider than the jar and 

 about twice this in length. Each damper was perforated by a 

 round hole, the diameter of the smaller hole being about 4 mm. 

 and the other about 10 mm. 



The experiments were performed as follows: — one jar was 

 clamped with its mouth upwards, aud on it were laid the two 

 dampers, and upon them the other jar mouth downwards. By 

 sliding the dampers it is easy to bring the jars into communication 

 either with each other or with the air. The jars having been 

 brought into communication and the stopcocks opened oxygen gas 

 was blown through until the air was displaced. 



The taps were then shut and communication between the jars 

 interrupted by sliding the dampers. The lower jar by the same 

 means was brought into communication with the air and an 

 approximately known quantity, either chlorine or ozone, blown into 

 it. The lower jar was then closed and the apparatus left to rest 

 for some hours to get rid of convection and other currents. The 

 taps were then opened for a moment to equalize the pressure and 



