KiNAHAX. — On the Clearing of Peaty Waters. 449 



taken at the head -n-aters, heing always retained for comparison along 

 the course, but more particularly with a sample taken where the 

 stream joined the main river. In the small brooks or tributaries the 

 waters cleared going down stream, but in the larger rivers very 

 irregular changes often occur, their waters being affected by the cha- 

 racter of each of the tributaries. 



The thickness of the stratum examined in the tumblers was about 

 4^- inches ; Avhich was found sufficient for all purposes in the field, as u 

 very slight alteration in the colour could be detected ; but for more 

 detailed and accurate purposes in the laboratory a thicker stratum is 

 desirable. 



In these peaty waters there appear to be two distinct colouring 

 matters, one producing a brown of various degrees of intensity, the 

 other an olive-green ; ^ the mixture of the two colouring matters in 

 proper proportion produces a brown-green, but as a general rule the 

 former obscures the latter. 



It may be here pointed out that no correct estimate of the altera- 

 tions in the depth of tint of peaty colouring matter that take place 

 along the course of a stream can be formed by only looking at the 

 waters in the stream; because the thickness of the stratum of water 

 looked at, i. e. the depth of the river, may change, and the bottom 

 of the river may be variously coloured : some marked changes, however, 

 may be detected by observing the difference in the colour of the foam 

 that forms at the different small falls along a stream. 



By the method as sketched out above, the principal tributaries belong- 

 ing to the Ow and Avonbeg were carefully examined from their head 

 waters to their junction with the main rivers, and their effect on 

 each main river, if any, was noted. This was done by comparing a 

 sample taken from the main river just above where it was joined by 

 the tributary, with one taken below the first fall or rapid that oc- 

 curred after their junction, where their waters would be well mixed. 



The examination of the streams was repeated during different 

 stages of flood, and different seasons of the year. It appears that, as 

 a rule, the streams are more peaty in summer than in winter ; and that 

 after continuous dry weather the peaty matter is much reduced. During 

 cold frosty weather, or when thej'e is snow on the mountains, very 

 little peaty colouring is found in the streams. 



The Ballynagappoge brook, which drains the N.W. slope of Croagh- 

 anmoira and discharges into the Ow, affords, as previously pointed out, 

 much instruction. When examined during the summer it was found at 

 its head waters to be of a deep brown, but when it joined the Ow 

 after a flow of about \\ miles with a fall of about 500 feet it had become 

 quite clear and limpid ; all its feeders are peaty, except a small one 

 that enters it below Rosahane-bridge after the principal decolourization 

 has taken place. Tnis brook therefore may be described in detail. 



1 I find that Dr. Tidy states {Chem. Soc. Jour., 1880, p. 293), that the brotcti 

 colour is due to old peat, the olive-green to more recent peaty matter. 



