140 



Proceedings of the Royal Irish Academy. 



another voliime of the water, until the apparatus becomes incon- 

 veniently full. I usually made from four to six such experiments in 

 each case. The temperature of the apparatus must be kept at about 

 50^ C, by the addition of warm water at intervals ; the amount of 

 hyposulphite required becomes gradually less as the apparatus cools, 

 giving the results too low. 



To test the accuracy of the method, I took a measured volume of 

 the same water at the time of the experiments, expelled the gases by 

 boiling, collected this gaseous mixture, and determined its volume and 

 composition by the usual methods of Bunsen's gasometric analysis. 



The following examples are taken, to illustrate the method of ana- 

 lysis. 



Volumetric Method. 



jMean of four determinations gave 



25 cub. cents, indigo = 8"21 cub. cents, hyposulphite. 



This quantity of indigo we before found to yield 1-398 cub. cents, of 

 oxygen. Therefore 



8-21 cub. cents, hyposulphite = 1-398 cub. cents, of oxygen. 



Mean of five determinations gave 



3-55 cub. cents, hyposulphite = 75 cub. cents, of water. 



Prom this we find the quantity of oxygen contained in 2-420 litres of 

 water — the volume used in the gasometric method. 



2-420 litres of water contain 19-505 cub. cents, of oxygen. 



Gasometric Method. 



Yolume used, 2-420 



Temperature of water, . . . 13° C. 



litres. 

















= ft 





Volume. 



Tempera- 

 ture 



Pressure 





> 1 «- ' 



"Uo E 







in o°C. 





° h 



" ° S 

 t"^ 



Total vol. of Gas evolved, . 



302-56 



13-9 



737 



268-8 



237-719 



After absorption of CO2, . 



316-149 



14-9 



745 



229-2 



193-959 



■ After the admission of H, . 



503-6 



14-4 



765 



55-2 



439-066 



After explosion, .... 



325-96 



12-4 



771 



230-5 



217-337 



