534 EEPORT— 1880. 



The following Eeports and Papers were read : — 



1. Report of the Committee iipon the Present State of our Knowledge of 

 Spectrum Analysis (^Spectra of Metalloids'). — See Reports, p. 258. 



2. Report of the Committee upon the Present State of our Knowledge of 

 Spectrum Analysis {Ultra-violet Spectra). — See Reports, p. 258. 



3. An Improved Volumetric Apparatus loas exhibited 

 hy J. W. Starling. 



4. On the Coal Seams of the Eastern Portion of the South Wales Basin 

 and their Chemical Composition. By J. W. Thomas. 



5. On a New Mode for the Purification of Sewage. By P. Spencb. 



The question of the disposal of sewage is still an unsettled one, and is becom- 

 ing daily more pressing. 



To our large towns it is now a most serious matter ; the rivers that flow past 

 many of them are assuming the character of pestiferous sewers ; fish have ceased 

 to live in them, and are gradually dying out from others ; and, excepting where 

 to%vns are near the sea, the rivers will become nuisances to an extent that will be 

 unbearable. 



Many schemes have been tried and some are now in operation, by which 

 sewage has been partially or completely purified ; filtration and irrigation can be 

 made to effect the object, but have chiefly been tested in small localities, and they 

 are, I believe, tacitly oiven up as applicable to large populations. 



Precipitation by lime is now practically the mode by which, not purification, 

 but partial clarification is conducted, and by which the demands of the law are 

 not met, but merely evaded. Dr. Angus Smith, one of the Government in- 

 spectors under the Rivers Pollution Act, gives as the result of many analyses of 

 lime-efiluents, that while the solid sludge of the sewage is precipitated and the 

 liquid is thereby clarified, it still contains nearly all the soluble putretiable matter, 

 and is really a very impure fluid. 



Where, in addition to lime-clarification, subsequent irrigation with the effluent 

 is practicable, it is rendered nearly pure ; and where, in connection with lime, salts 

 of alumina are used in sufficient quantity, the water or effluent is pure, limpid in 

 appearance, free from colour, smell, and putridity. 



Having been engaged for some years in producing, in a cheap form, a sulphate 

 of alumina suitable for purifying sewage, and which is at the present moment 

 used by nearly all who are purifying by alumina, I have necessarily had my 

 attention directed to tlie problem of the best mode of precipitation by which the 

 aluminous salt, which is still an expensive substance, coidd be economised, and the 

 sewage completely purified at the smallest cost. AVhere alumina is used various 

 other substances have been and are now used in connection with it ; these are blood, 

 clay, charcoal, iron salts, and other bodies of more or less efficiency: none of these 

 substances are, I belie'^e, essential to the process, and some of them are probably 

 useless. 



Lime is in nearly all cases needfid to the efficiency of the aluminous salts, 

 excepting in those where the sewage is decidedly alkaline ; but as this condition 

 cannot be depended upon, it may be taken for granted that lime should always be 

 used. 



In the new scheme which I shall now describe, I commence on the basis of 

 the lime-process as now conducted, and assume that it is so far useful and is a 

 preparation for real purification, and I propose to take the effluent as it comes 



