STERILIZATION 179 



rater has drained away. Such a material has high oxidizing 

 powers, the expense being the main objection. 



Bertrand/ in his investigation of oxydases (p. no), pointed out 

 the invariable presence of traces of manganese, and suggests 

 that the oxydases are compounds of manganese in which the 

 acid radicle is of a proteid character, and of sufficient activity 

 to keep the metal in solution, whilst the manganese is the real 

 carrier of oxygen. Antoine Villiers^ and Achille Livache^ 

 confirm this view of the agency of very small quantities of 

 manganese in transferring oxygen from one compound to 

 another, and it seems probable that the traces of manganese 

 in coke, clinker, and other materials of filter-beds may be help- 

 ful to oxidizing action by supplying this element to oxidizing 

 ^enzymes. In the natural oxidations that occur in ferruginous 

 '^aters, the action of enzymes has also been asserted. 

 Adeney, in 1894,* observed that the sludge from sewage that 

 lad been treated with manganate of soda slowly evolved 

 ^arbonic acid and nitrogen gas. This oxidation of the organic 

 latter was clearly traced by him to the available oxygen of the 

 lydrated peroxide of manganese in the precipitate, as he found 

 :hat the peroxide became completely converted into manganous 

 carbonate, MnCOg. The process is exactly parallel to denitrifi- 

 \ation (p. 125), and is similarly dependent on organisms, as 

 [cWeeney^ found that in sterilized media the reduction of 

 jroxide to carbonate did not occur. In his " Oxynite " 

 )rocess the sewage first deposited nearly 90 per cent, of the 

 iolid matters " unmixed with precipitating chemicals," and 

 [hen was precipitated by manganate of soda and sulphate of 

 lumina; this sludge underwent the spontaneous oxidation 

 lescribed above, and admits of the recovery of the manganese.^ 

 'he effluent was mixed with nitrate of soda to supply more 

 >xygen. 



Chlorine and Chlorine Compounds as conveyers of oxygen have 

 >een often used. Chlorine by itself may act in different ways, 

 'hen concentrated it can combine directly with organic 

 latters or replace the hydrogen in them, precipitating all 

 Ibuminous substances^ and rendering them imputrescible, 



^ Comptes Rendus, 1896, cxxiii., 463, and 1897, cxxiv., 1355. 

 2 Ibid., 1349. 3 jhid^^ 1-20. 



^ Proceedings of the Royal Dublin Society, viii., 247. 

 \ ^ Transactions of the Royal Dublin Society, August, 1897. 

 ** See also Wilson, Patent 1725, 1891. 

 ^ Rideal and Stewart, Analyst, 1897, p. 228. 



12 — 2 



