TRANSACTIONS OF SECTION B. 501 



the ammonia, and the gases after passing through a condenser are finally burnt 

 under any appropriate apparatus. This final combustion of the gases does away 

 ■with any nuisance, besides utilising a considerable amount of heat derived from the 

 combustion of the organic matters. 



Difi'erent nitrogenous substances require different treatment before being fed 

 into cupola No. 2. Shoddy, for instance, is a dry product, and the nitrogen con- 

 tained in it is the only substance of value, the ash being worth little. 



In preparing shoddy for this piu'pose, we make a large heap, watering the 

 shoddy with a dilute solution of soda, containing the same weight of carbonate of 

 soda as the shoddy contains nitrogen. The heap of shoddy gradually heats and 

 diff"uses the moisture equally throughout the mass. This prevents the dust being 

 carried over by the current into the saturator. 



Before charging the prepared shoddy into the cupola it is mixed with about 

 G per cent of lime, in a moist powdery state. By this treatment 80 per cent, of the 

 nitrogen is converted into ammonia. The ash-dust and lime fall to the bottom, 

 and are withdrawn as they accumulate. This material is used as a manure. 



In applying this principle to nitrogenous matters containing phosphates, such as 

 fish or excreta, no lime or soda is added, and it is thus more of an economical 

 method of drying up these substances than combining their nitrogen into ammonia. 

 But even in drying part, carbonate of ammonia comes over, which is absorbed by 

 the sulphuric acid. 



The dried matter, withdrawn as it accumulates, consists principally of phosphates, 

 nitrogenous carbon, and potash. This residue, added to either fish or excreta in 

 an offensive state, completely deodorises it, so that the operation can be carried on 

 without a nuisance. The pressure under which the apparatus is worked must be 

 sufficient to drive the gases and absorbable material through the saturators. A 

 quantity of tar and animal oil gradually comes over and accumulates in the catch- 

 box. 



The author has not had much experience in applying this principle to the drying 

 up of excrements such as that obtained by what is called the Rochdale tub system, 

 but he has done sufficient to justify him in saying that it can be economically ap- 

 plied to that purpose. 



In his experiments with excreta, instead of using an upright cupola, he used a 

 long horizontal reverberatory furnace, heated on the frame principle, by gases 

 generated in a separate cupola, and burnt so as to leave no free oxygen. The 

 whole of the carbonate of ammonia is expelled at the boiling temperature, and is 

 retained in the saturators. 



The residue is a dry carbonaceous powder, containing all the inorganic con- 

 stituents of the excreta. 



