PUEIFICATION OF EEFUSE WATER. 52o' 



little coloring or impure matter. The water flowing from the third pit iS' 

 generally so pure that it contains nothing but the superfluous lime and 

 the soluble salts formed by it. 



The quantity of superflous lime is generally very small, as lime only 

 dissolves in 500 parts of water; but it might nevertheless, prove injurious 

 to the fish. It is therefore necessary to lead off the water in open ditclies, 

 as lime very quickly becomes impregnated with carbonic acid from its 

 immediate surroundings or from the air ; the carbonated lime is then 

 separated, as well as the last remnants of coloring matter. The water 

 which has passed through these ditches will thus enter the river in a 

 perfectly pure condition, and it is not even necessary to let it flow through 

 such open ditches for any considerable distance. It has also been pro- 

 posed to let the pipe through which the water finally flows into the 

 river open from below, about the middle of the bottom, so that the refuse 

 water might immediately mingle with a great quantity of river water, 

 and thus be deprived of anything of an injurious character which might 

 have remained in it. 



In most cases, however, the application of lime is sufficient to purify 

 the water. In my former treatise on this subject I have entered into 

 details, and will here only mention a few instances of purifying water. 

 Soapy or fatty matter will generally be separated from the water by 

 lime. These, however, are special cases, which were mentioned in my 

 former treatise in order to show the value of the method. These lime 

 deposits form very valuable fertilizers, so that, according to observations 

 made in England, the expenses of this purifying ]3rocess are fully covered. 

 The whole arrangement is not at all expensive, and if once introduced 

 it onlyrequires a Little attention to make it pay. Two pits are frequently 

 sufficient to purify the water. 



In Saxony the government ordered an investigation* to ascertain the 

 number of complaints of water having been made impure by refuse. In 

 1877 complaints were made in 140 places and traced to 273 sources. 

 Half of all these cases were traced to the weaving industries, especially 

 dyeing, bleaching, and wool-weaving; 9 per cent, to the manufacture 

 of paper; 8 per cent, to the manufacture of leather; 8 j)ercent. to min- 

 ing industries ; 6 i^er cent, to the manufacture of articles of food ; 2 per 

 cent, to the manufacture of chemicals. Of the 620 breweries in Saxony 

 only 6 were accused of rendering public water-courses impure. 



I found that many brewers have introduced purifying pits in connec- 

 tion with their establishments, and have worked them very successfully^ 

 as the mud obtained from these pits forms a most valuable fertilizer. 

 In one case I was enabled to get a better insight into this question and 

 to render aid. 



A large brewery was accused of making the water in a large neigh- 

 boring i)ond so impure by refuse water that it began to putrefy, thus 

 causing considerable damage to the pond and annoyance to the people 

 living near it. A chemical analysis of some of the most turbid refuse 



^GuNTHER, " BerJiner Klinische Wochemchri/t," 1879, No. 6. 



