[ 459 ] 

 LXXIII. Intelligence and Miscellaneous Articles. 



ON THE PRODUCTION OF OZONE By THE DECOMPOSITION OF 

 WATER AT LOW TEMPERATURES. BY M. GORET. 



IN some experiments in which I employed a voltameter cooled in a 

 mixture of ice and common salt, I observed that the gas evolved, 

 which was to be carried through drying tubes, attacked and quickly 

 ate through the caoutchouc tubes uniting the difterent pieces of the 

 apparatus. When the voltameter was not cooled, the caoutchouc 

 completely retained the gas. It appeared to me that this corrosive 

 action must be due to the presence of a larger quantity of ozone 

 when the decomposition of water is eiFected at a low temperature. 



I endeavoured to ascertain this quantity in the following manner. 

 Ozone, like chlorine, possesses the property of converting arsenious 

 acid into arsenic acid. If, then, we employ a standard solution of 

 arsenious acid, of such a strength that it requires 1 litre of chlorine 

 to convert the whole of the arsenious acid in 1 litre of the solution 

 into arsenic acid, by passing the gas evolved by the pile through 50 

 cubic centimetres of this solution, the ozone contained in the gas 

 will effect the conversion of a certain portion of the arsenious acid. 

 For the determination of the quantity which has undergone this 

 change, it is sufficient to compare the quantity of hypochlorite of 

 lime required to complete the oxidation of the arsenious acid into 

 which the gas has been passed, with the quantity necessary to con- 

 vert the whole of the arsenious acid contained in 50 cubic centi- 

 metres of the normal solution into arsenic acid. 



Let N be the number of cubic centimetres of a certain solution of 

 hypochlorite of lime required for the conversion of 50 cubic centi- 

 metres of the normal fluid into arsenic acid, a change which is indi- 

 cated by the decoloration of a drop of indigo. 



Let N' be the number of cubic centimetres of the same solution 

 of hypochlorite of lime required to produce the decoloration of a 

 drop of indigo in 50 cubic centimetres of the solution of arsenious 

 acid previously partially oxidized by the action of the ozone. 



Then the quantity of ozone which has been absorbed will have 

 produced the same effect as x cubic centimetres of chlorine, 



N : N — N' : : 50 cubic centims. : x; 

 and if we suppose that 1 cubic centimetre of ozone is equivalent to 

 2 cubic centimetres of chlorine, - will express the number of cubic 



centimetres of o:...ne. 



But in order to ascertain the proportion of the quantity of ozone 

 to the quantity of oxygen evolved, the volume of detonating gas 

 produced must be measured. With this view I employed two vol- 

 tameters traversed by the same electrical current. One was furnished 

 with a conducting tube, which conveyed the gas to a gauged receiver 

 placed on the water-trough. As the two voltameters disengage, at 

 all events, very nearly the same quantity of gas, the projjortion of 

 oxygen produced by the other apparatub may be very well ascer- 



