When I see the housemaid's pail filled with three gallons of soapy water and perhaps a pint of urine, am I to believe that the addition thereto of five ounces of solid excrement, a second half pint of urine, and a square foot of paper, will make no difference to its foulness and cause no increase of difficulty in its purification? _Credat Judæus Apella!_ Such a statement is manifestly absurd. Again, we must remember that it is the solid excreta which constitute not only the foulest but the most dangerous ingredient of sewage, the only one which has caused widespread epidemics again and again, the one which has hung a load of debt round the neck of every municipality in the country. The other ingredients of household slops, unlike the fæces, are little liable to contain pathogenic microbes. The urine of a healthy man is, as we all know, sterile when passed. In diseased conditions it may occasionally possess infective power, but this is a speculation rather than a practical fact acknowledged by the sanitarian. A large proportion of cooking-water has been boiled, and is therefore sterile, and the same may be said of the water in which our linen has been washed. Household slops, therefore, are not liable to be really infective. They are nitrogenous, and consequently, if allowed to stagnate by mismanagement, they become very foul from decomposition, but that they are capable of producing epidemics has not yet been proved. Between excrement and slop-water there is this difference, that solid excreta are foul-smelling _ab initio_, but slop-water (if we except the smell of water in which cabbage has been boiled) only becomes foul if it is mismanaged. In places which are not overcrowded a great deal has been done when the wholesome treatment of the solid excreta has been arranged for, and I feel that to neglect the doctrine that 'half a loaf is better than no bread,' and to discourage people from dealing with solid excreta, because they do not see their way quite clearly for the disposal of slops, is most dangerous. One thing is certain, viz., that if the solid excreta are dealt with by dry methods the liquid sewage will be 25 per cent. less bulky than otherwise would be the case. I feel sure that if, in our anxiety to prevent the pollution of rivers, we fail to appreciate the biological differences between excrement and slop-water we shall make a mistake, which in the end will be no real advantage to the streams. If, therefore, villages and places where the population is sparse make serious efforts to deal with excreta, they should have at least some breathing-time allowed before the fish in their streams are deprived of the luxuries which they doubtless obtain from kitchen slops.