KiNAHAN — Report on the Clearing of Peaty Waters. 599 



precautions were taken that nothing likely to mar the results should 

 occur. In estimating the organic constituents duplicate analyses were 

 made in most cases, and in the weighings for the organic carbon the 

 allowable error was taken as under three-tenths of a milligram.^ 



These results seem clearly to show that simple aeration is inca- 

 pable of eflfecting the removal of the peaty matter. The Powerscourt 

 samples were taken in summer, on a warm sunny day, when the 

 waters were deeply tinted with peaty colouring matter, yet the diffe- 

 rence between the two samples is practically nothing, although the 

 fall is 360 feet, and the aeration exceptional. In the Glenmalure 

 water we have samples taken on a fine day in winter, when the quan- 

 tity of peaty matter was not excessive ; and although in this case the 

 fall is over 700 feet, the two samples are practically identical. 



In the samples taken from the Ovoca river the results obtained are 

 of quite an opposite character to those of the two preceding samples : 

 here there is but a fall of 50 feet in a flow of three miles, and aeration 

 can have but a slight effect. That the active agent is the mineral 

 drainage, which enters the river in the intermediate portions, seems evi- 

 dent from the results of the experiments given in the previous Eeport. 



The nature of these mineral waters we now propose giving a brief 

 sketch of ; but before doing so it seems desirable to give some account 

 of the head waters of the river, more especially as all at some time 

 have received more or less mine drainage. 



The Principal Mineral Impurities of the Ovoca. 



The present Ovoca river*' is formed by the junction of the Avon- 

 more and Avonbeg, at the Upper ''Meeting of the "Waters," and flows 

 into the sea at Arklow, having been joined by the Daragh water, or 

 Aughrim river, at Woodenbridge, or Lower "Meeting of the Waters." 



side red ; the two differently-coloured waters going separately over the weir to be 

 sKghtly mixed below, but tbe great mixing does not take place until tbey reach the 

 Falls of Doonass, below whichthe red ferriferous waters are found to have cleared 

 out the peaty colouring matter. The waters flowing over the falls are more often 

 coloured with peat than otherwise. While living at Castleconnell some of the 

 largest floods I saw on the falls were black ones. When the rain falls only to the 

 southward of the Shannon, the ' black flood,' going over the fall, is met by a ' red 

 flood,' coming out of the Annacotty, or Mulkear river, which neutralises and 

 destroys the peaty colour in the water before it reaches Limerick. On account of 

 the difference in the land on each side of the Shannon above Castleconnell the 

 waters on each side of the river above the falls must give very different analyses." 



5 This would be as carbonic acid, so that the carbon would be -^ of this, or 

 about one-tenth of a milligram, which was usually on a litre of water ; but in the ana- 

 lyses of Nos. v., VI., VII., and X.— XIII. where only 500 cc. water was used, the 

 error was larger than this. The figures given in the Table are the means ; except 

 in those cases on which inferences are based, when the two results are stated, viz. : 

 Nos. III. and IV., VIII. and IX. 



6 Formerly the river, as far down as Woodenbridge, was included in the Avon- 

 more, whUe the river beloAV this, in some accounts of the district written in the last 

 century, is called the " Ovo." 



