i873-] A Solution of the Sewage Problem. 69 



Black Tartarian Oats. 



lbs. ozs. 



Native Guano, 15 cwts. per acre ..68 

 No Guano 3 14 



These results are worthy the attention of the farmer; but 

 they are in no way surprising, for it is universally admitted 

 that town sewage has manurial value ; and as the ingre- 

 dients of the ABC process which are added to the sewage 

 have no destructive effect upon the constituents of the sewage, 

 it would be a matter of much greater surprise if the 

 " native guano " were found to be without manurial value. 

 Further evidence in favour of the manure is, that there is a 

 demand for it at the rate of £3 10s. the ton. That at 

 Crossness the manure has cost more than this sum to pro- 

 duce is extremely probable, for the machinery, steam-engine, 

 and tanks have been apparently arranged with the object of 

 getting the minimum of work at the maximum of expense. 

 Probably some of this is due to the necessity of erecting 

 works before the most advantageous method of carrying on 

 the process had been ascertained, whilst some of the appa- 

 rent waste of money may be rendered necessary by the show 

 character of the works, and the necessity of having every- 

 thing aboveground to answer the accusation of improper 

 dilution of the effluent. But when it is considered that 

 fifteen times as much coal is being burnt there* as was suffi- 

 cient for the same work at Paris ; that the alum is costing 

 three or four times as much as it need ; that an experienced 

 chemical superintendent is included among the staff; that 

 the rest of the staff is about twice as numerous as need be ; 

 and last, though not least, that for the greater part of the 

 three months' official trial, the sewage which has been 

 treated has been excessively dilute, owing to heavy rains : — 

 when all these extenuating circumstances are considered, 

 the wonder is, not that the " native guano " produced at 

 Crossness has exceeded £3 10s. per ton, but that the price 

 has not risen to twice that figure. Let us turn to other 

 works conducted on some approach to economical prin- 

 ciples, and a very different result will be seen. 



At Paris the expenses are higher than need be, owing to 

 their being show works, and necessarily conducted with 

 some disregard to economy. The works being simply for 

 experimental illustration, were carried on intermittently, 

 and were seldom in full operation, except when visitors 



* This does not include coal used for artificially drying the "native guano " at 

 Crossness. 



