THE EARTH-CLOSET SYSTEM. 925 



became yellow and turbid, and finally threw down a very abundant 

 red precipitate. 



%, The same quantity of solution of ammonia having been 

 poured into a jar of the same size as the one employed in experi- 

 ment No. I, dried earth was poured into the jar up to about the 

 level which the lOO cubic centimetres of water occupied in the 

 other jar. The jar having been similarly connected on either 

 side, and aspirated, Nessler's reagent became turbid and yellowish, 

 but gave no very distinct precipitate, and none at all of a red 

 colour. 



3. Ashes from a coal fire having been substituted for the dried 

 earth of experiment No. 2, this experiment was again tried, with 

 the result of the formation of scarcely any precipitate in the bulbs 

 containing Nessler's reagent. 



4 and 5. These experiments consisted in repeating experiments 

 Nos. 1 and 3 severally, with the addition to the earth and ashes 

 respectively of as much water as the jars would receive into the 

 space already partially filled with the solid substances specified. In 

 each case a large quantity of yellowish-red precipitate was formed 

 in the test fluid upon aspiration. The precipitate was much less 

 dense and abundant than that produced in experiment No. i, and 

 took a much longer aspiration before it was formed. It was 

 formed much more rapidly by the air aspirated from the wetted 

 earth than by that from the wetted ashes. 



It will be asked. Do not these experiments show that ashes and 

 earth are, each of them in their respective order, superior to water 

 for use in closets ? I think not ; for, firstly, it is not certain that 

 ammonia is the cause, or a necessary co-efiicient of the cause, of 

 miasma, any more than it was proved formerly by Daniell that 

 hydro- sulphuric acid was the cause of malaria. Secondly, there is 

 much reason to believe that it is precisely when the earth receives 

 choleraic and typhoid evacuations, and should, ex hypothesis disinfect 

 them, that they become most deadly. (See Pettenkofer, ' Zeitschrift 

 fiir Biologic,' 1865, p. 357, et passim \ Liebermeister, 'Deutsche 

 Klinik,' Feb. 17, 1866 ; Varrentrap, loc. cit., p. loi ; Parkes's 

 ' Hygiene,' pp. 254, 593, ed. i.) The healthiness of Alexander's 

 armies has been ascribed to his practice of frequently changing his 

 camping-ground, and army surgeons nowadays recommend the like 

 practice, or disinfect the ground itself, as the French did in the 



