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or phosphoric acid, but contained a comparatively large 
proportion of magnesium carbonate; which was kept in 
solution by the ammonium salts and free carbonic acid; 
the presence of this magnesium salt would no doubt account 
for the absence of phosphoric acid. 
Fifth. The sediment and solution are practically free 
from bacteria or other animalcula. 
Sixth. That when the residue from a large proportion of 
the water is heated to redness it produces no charring nor 
smell. 
It might be interesting here to compare a few of the 
results of this analysis with those from a water which I col- 
lected about the same time which drained during a 
heavy rain from decomposing animal matter; principally 
butchers’ offal, which had not been treated with charcoal. 
It contained 
Drainage from Animal Matter without Charcoal. 
Grains per Gallon, 
Total solid matter left on evaporating to dryness 
and heating at 220° F. till it ceased to lose 
weight 272'335 
Matter lost hy prolonged heating to redness 118'475 
Saline matter 153’860 
Free ammonia 15*447 
Chlorine 13*394 
Oxygen required hy potassium permanganate test 85*629 
When the dry residue was heated to redness it emitted a 
very bad smell at first, and afterwards the smell of burning 
hair. 
Microscopic examination showed abundance of animalcula 
swimming about in all directions. 
The charcoal with which the night-soil had been mixed 
deserves some notice. It was that produced in the manu- 
facture of prussiate of potash by the charring of animal 
refuse such as hoofs, hair, leather, v/oollen rags, &c., so that 
although it is really “ animal charcoal,” it differs very much 
from the substance usually known under that name, viz. 
