708 REPOKT— 1900. 



suds and effluents and two millions of dyeworlrs effluents, with over half a million 

 gallons from ^lessrs. Lister's, of Manningbam Mills. Frooi experiments upon 

 ■bulks of 20,000 gallons, a mixture of one part of wool-suds and seven parts of 

 Bradford Sunday sewage requires nine times as much precipitant, and produces 

 ten times as much wet and twelve and a half times as much settled sludge, as the 

 Sunday sewage alone. A number of the woolcombera recover part of the wool- 

 grease by 'cracking' the crude suds with oil of vitriol. The effluent so obtained 

 is very acid, contains from 100 to L'OO grains of grease per gallon, with a very 

 large amount of nitrogenous impurities. The difficulties arising from the pre- 

 sence of the wool-suds and effluents are twofold: (1) The peculiar emulsive 

 character of wool-grease ; (2) the excessive amount of nitrogenous impurities. 

 "With Bradford sewage have been tried : — 



(1) Lime, giving a clear but bad effluent with a large amount of sludge. 



(2) Copperas, followed by lime, producing a lurbid but better effluent. 



(3) Alumina-ferric, i.e., alumina sulphate, giving unsatisfactory results at a 

 high cost. 



(4) Acid ferric sulphate, giving a high degree of purification, but with an 

 acid effluent. 



(■")) Neutral ferric sulphate, yielding as good results, but with less acidity. 

 (6) Basic ferric sulphate, giving a 02 per cent, purification and a neutral or 

 slightly alkaline effluent.' 



The basic sulphate is made at the sewage works by McCulloch's Patent. As 

 it is necessary to use a considerable weight of the basic salt, the method proves 

 costly. 



The author has fully investigated the biology of Bradford sewage, and has 

 tried diflerent methods of bacterial treatment. It has not been very difficult to 

 get nitrification with as high a purification in extreme cases as 70 per cent. 



The grease present to the extent of 40 to 50 grains per gallon very soon 

 chokes up the filters. There can be no doubt that if the woolcombers' euds and 

 effluents were entirely removed the whole of the city's sewage could be 

 treated biologically, with an immense saving in the cost of chemicals and the 

 treatment of the sludge. Failing the elimination of the wool-suds the best 

 method would seem to be a preliminary treatment with the cheapest precipitant 

 obtainable and the biological purification of the efiluent, either on bacteria beds or 

 on land, preferably on both. 



Several patentees have experimented on Bradford sewage, but hitherto with 

 unsatisfactory results, and they have all retired from the attempt, saying that the 

 grease baffled them. 



After describing the chemical and biological methods in detail, the author 

 entered at some length into the scientific causes of the difficulties of treatment. 



?. On (ha Treatment of Woolcombers' Effluents. By W. Leach, 



3. On a Simplr and Accurate Method for estimating the Dissolved Oxygen 

 in Fresh Water, Sea Water, Sewar/e Efflueyits, &c. B%i Professor Letts, 

 D.Sc, Ph.D., dr., and II. F. Blake, F.I.C, F.C.S., Queen's College, 

 Belfast. 



After criticising the existing mpthous for determining the dissolved oxygen in 

 w-ater voliunetrically, tlie authors describe a very sin)i)le and accurate method for 

 the purpose, of which the following is an outline : 



An ordinary separating funnel is filled with the water to be examined, and a 

 •measured volume Avithdrawn. A definite volwme of standard ferrous sulphate 

 solution is then added, and afterwards ammonia — the volume of these two reagents 



' This effluent, after passing at a rapid rate through fine breeze beds, gives an 

 additional 9 per cent. o£ purification, although no nitrification occurs. 



