602 Proceedings of the Royal Irish Academy. 



A short distance lower down, on the same bank, a small stream 

 enters at Tinnahinch, coming from a spa, and also receiving the 

 drainage from the waste heaps along the mine tramway. The waters 

 were clear, but an ochreons precipitate settled out on exposure to the 

 air ; they are acid, but rather weak mineral waters. 



On the opposite or left bank, some distance lower down, above or 

 north of the village of Newbridge, a small stream — the Sulphur 

 brook — enters : formerly this was the principal source of mineral im- 

 purity to the Ovoca river, as it received all the drainage from Upper 

 Cronebane and most of that of Connary; but this now flows out at 

 Tigroney, and the mineral matter in the stream is derived from the 

 waste heaps, or attals, on the surface : considerable quantities of ochre 

 have been deposited along its course. 



Below this a small stream enters, on the right bank, at Castle- 

 macadam ; it drains the lands about the Ballymoneen mines, which 

 some time ago were worked for sulphur and iron ores ; it is now, how- 

 ever, free from injurious mineral impurities, and is inhabited by small 

 fish. 



This short sketch of the mineral drainage from the Ovoca mines 

 shows that by it a large amount of salts in solution pass into the 

 Ovoca river : this is evident both from the quantities of solids in each 

 of the samples, and from the fact that the total solids in average sam- 

 ples of the river water increased from 4" 8 8 parts, at Tigroney weir, to 

 9-26 parts per 100,000, or very nearly double, at the Black Dog. No 

 true estimate, however, of the total quantity entering can be made, as 

 such would require a series of careful measurements and analyses of 

 each stream, at different seasons of the year. Though these mineral 

 waters have the general effect of freeing the Ovoca river from organic 

 impurities, the river, on the other hand, is literally poisoned by them ; 

 and no fish are to be found in it from Tigroney weir to the sea at 

 Arklow. 



Conclusions. 



In this Eeport I hope it has been clearly shown : — 



That the colorometric method of examination of peaty waters, 

 adopted in the first part, is a fair relative, although not an absolute, 

 method of analysis. 



That the action of the air which the water of a river is subjected to 

 is incapable of oxidizing the peaty matter, either in winter or summer, 

 even when the natural conditions are most favourable, as when the 

 waters are dashed into foam down a steep and great height ; and that, 

 therefore, the same will be true, a fortiori, in a slow and sluggish 

 river, where only the surface is exposed to the action of the air. 



That the results of the laboratory experiments given in the first 

 part are supported by what takes place in some rivers, and that the 

 soluble salts of alumina, iron, and manganese are capable of removing, 

 and do actually in nature remove, the peaty colouring efficiently and 

 rapidly. 



