As far as my experiments have as yet gone, I have not discovered the limit of sawdust for dealing satisfactorily with urine. Thus in 1894 I filtered during May, June, and July, 39 lbs. weight of urine through 6 lbs. of sawdust in a flannel bag, and neither filtrate nor sawdust was in the least offensive. In the same months in 1895 I passed an additional 41 lbs. weight of urine through the same sawdust in the same bag, and practically with the same result. In 1896 I added over 30 lbs. weight of urine to the same sawdust, but as the flannel bag had become too rotten to hold together, I was obliged to have recourse to the metal filter-vessel. The early filtrate obtained in 1896 had a specific gravity of 1·061, but, like its predecessors, could be evaporated to dryness without offence, and the sawdust was not in the least malodorous, although it was distinctly (as it always has been in these experiments) ammoniacal. One of the most interesting experiments was that in which the filtering material consisted of crumpled paper in a flannel bag. The paper used was such as is familiar to every one, and was derived from old Bradshaw's Guides, the leaves of which were torn out and crumpled up in the hand before being put into the bag. This paper, like most paper used for printing, is sized and not very absorbent. At the end of a week a considerable quantity of filtrate had been obtained, and both filter and filtrate became excessively foul and malodorous, so that it was unpleasantly obtrusive, even when one stood several yards from it. The foul filtrate was returned to the filter, and no fresh urine was added for a time. This was done on October 15, and on October 21 all had become sweet, and four ounces of a perfectly sweet and _faintly acid_ filtrate were obtained! The filter never became foul after this date. Between October 21 and November 25, 1894, 434 ounces of urine were added, and 54¼ ounces of filtrate were obtained. Between November 25, 1894, and January 6, 1895, the filter rested; then, between January 6 and March 31 urine was added only occasionally, so that the total only amounted to 560 ounces (35 lbs. weight). Three and a half pounds weight of filtrate were obtained. The filtrate was more ammoniacal than that obtained from sawdust, earth, or peat, but it never has shown any tendency to putrefy. The paper became blackish, and was riddled with fungi, and ultimately was scarcely distinguishable from garden mould. Thus I have shown that these absorbent materials exercise a strangely purifying power upon urine, and its behaviour with these bodies is very different to what is observed when urine is mixed with water. Now for the practical application. I am not going to advocate that all houses in cities should be fitted with absorbent urinals, but it will occur to many that there are circumstances when such urinals may be very useful.