KiNAHAN. — On the Clearing of Peaty Waters. 447 



LXVI. Repoet OH" THE Cleaeikg of Peatt Watees. Paet I. By 



GeEEAED a. KrN-AHAN". 



[Read, May 9th, 18S1.] 



Introduction. 



In the spring of 1880 Professor Hartley, P.R.S.E., suggested tliat I 

 should make certain experiments on peaty waters, as he had observed 

 that some peaty streams become rapidly decolourized, while others 

 flow for considei'able distances without undergoing any alteration. 

 Besides furnishing me with some observations and the results of 

 some experiments he had made, he desii'ed me to direct my attention 

 specially to the action of clays, and the more commonly occurring 

 lime salts, in order to determine whether they or natural oxidation 

 of the peaty matter played the more important part in the decolouriz- 

 ing of peaty streams. 



Professor Hartley had remarked that along the course of the River 

 Affaric, in Invernesshire, flowing from Loch Affaric through Loch Bene- 

 vian to join the River Grlass, a distance of about sis miles over a hard 

 rocky bed (quartzite, micaceous schist, and basalt), no alteration in 

 the colour of the water was detected, though for three weeks while 

 the observations were carried on no rain fell, and there was abundance 

 of sunshine, the stream being frequently lashed into foam along its 

 course. 



He found that peaty waters can be partially purified by an 

 admixture of hard water of about 26° of hardness on Clarke's 

 scale. Also that when a mixture of hard water and soft peaty water 

 was softened by adding lime water, the calcic carbonate carried down 

 much peaty colouring matter, the piuification being more effectual 

 than in the last case. 



He ascertained also that about two to three grains of sulphate of 

 alumina were sufficient to decolourize ten gallons of darkish peaty 

 water, the dark brown matter settling down in about twenty-four 

 hours. Prom this it might be anticipated, as was actually proved by 

 experiment, that certain clays, when mixed with the water, would 

 have a similar effect. 



Professor Hartley also remarks that Mr. J. Y. Buchanan, late of 

 the scientific staff of the Challenger, has found that the water at the 

 bottom of some of the Highland Lochs is colourless, while the sur- 

 face water is peaty ; the material at the bottom being blue or white 

 clay. One particular instance of this occurs at Loch Ness, in places 

 where the water is from 50 to 110 fathoms deep. 



In this Report I propose to give, first, the field notes made on 

 streams in the Ovoca river basin, with the results of some of my 

 laboratory experiments suggested by these observations, to which aro 

 added some notes on the inferences to be drawn from both. 



