80 



Proceedings of the Royal Irish Acaoenii/. 



We now pr.oceedecl to the quantitative estimation of the respective 

 gaseous co^.rftituents. 



The total volume of gas given off by the known volume of 

 water was measured in a calibrated eudiometer, and in common 

 with the other readings reduced to the normal temperature and 

 pressure (0° C. and 760 m.m.s. bar. pres.) 



A portion of this gas was taken, transferred to another eudiometer, 

 and measured. After absorption of the carbonic acid by a potash 

 bullet, the gas was again read off by the kathetometer, the differ- 

 ence between the readings giving the amount of carbonic acid. 



Pure hydrogen evolved by electrolysis was then introduced, and 

 the volume then read off, to ascertain the amount of hydrogen 

 added. The spark given by a Rhumkorff's coil was then passed, 

 and after allowing it to cool, the resulting volume of the exploded 

 gases was read off : one-third of the contraction measures the amount 

 of oxygen present. 



The residual hydrogen in the gas having been deducted, the 

 remaining volume gives the amount of nitrogen present. From data 

 thus obtained, were calculated the percentage composition, the 

 absolute volumes in cub. cents, of the gases given off by the mea- 

 sured portion of the water employed ; and, from this last, the total 

 volume of the mixture contained in one million litres of water. 



AVe now proceed to give the results of some of our analyses of the 

 Vartry and Canal waters. The samples of the Vartry water were 

 taken from the taps in the Chemical Laboratories of the Royal College 

 of Science, Stephen' s-green, Dublin, being collected just before use: — 



No. 1.— Taken Ibth March, 1877. 



Volume used, 2-420 



Temperature of water used, . . . 7° C. 



litres. 





Volume. 



Tempera- 

 ture 

 in o°C. 



Pressure 

 in m.m.s. 



Ml 

 3 I 



>%°: ■ 



t "^ 

 c3 - 



Total vol. of gas evolved, . 

 After absorption of CO2, . 



Gas used, 



After the admission of H, . 

 After explosion, . . . 



180-347 

 169-296 

 282-362 

 412-130 

 255-990 



9-90 



9-45 



11-10 



10-80 



10-80 



740-5 

 751-0 

 752-0 

 752-0 

 752-0 



49-9 



52-8 

 288-1 

 166-0 

 300-6 



156-05 

 148-41 

 16209 

 300-63 

 143-12 



