30 
FACTS AND OBSERVATIONS. 
with the stomach, as it does not cause any irritation of the 
gastric surfaces. It may not, he says, supply iron to the 
blood-globules more promptly than do others, but it has an 
important property that hitherto has escaped attention, which 
adds new virtues to the iron, and bestows on this compound 
advantages possessed by no other. This arises from the 
phosphoric acid. Phosphorus, the elementary base of this 
acid, is a normal constituent of the body, being found in a 
free state in the great ganglionic nervous centres, and com¬ 
bined in various parts, as the brain-fat, bones, &c. It is also 
a constituent of certain nitrogenized proximate principles, 
and holds an important place amongst the other elements 
that contribute to cell-life and nerve-power; hence the thera¬ 
peutic value of this new salt. 
The tonic action of iron is well known. Phosphorus is 
regarded as a cerebral stimulant, exalting the action of the 
nerves directly, and that of the heart indirectly, and only a 
moderate degree beyond the normal tension. When the gan¬ 
glionic centres are wanting in their natural stimulus, many 
nervous and neuralgic diseases arise, which are often accom¬ 
panied with much debility; then it is found necessary to pass 
phosphoric acid into the blood, which can only be done by 
giving it in a saline state, with a base that would be assimilated, 
and thus it is set free. This is accomplished by the iron, which 
we know is appropriated by the haematosine of the blood. 
Composition of Sewage. —According to Dr. Letheby, 
the clear supernatant part of sewage contains a large quan¬ 
tity of amorphous organic matter, with the filaments of 
various fungi. It swarms with animal life, as beaded 
Spirulina, Vibriones, and Monads ; and soon after exposure 
to air the higher forms of infusoria appear, as Paramecium, 
Vorticella, Rotifera, &c. Besides which it contains small 
particles of animal and vegetable tissues, as the fibres of 
cotton, wool, &c. The sediment, which is black and gluti¬ 
nous, consists of the remains of undigested food, as muscular 
fibre, husk and hair of wheat, the cells and starch of potato, 
and the tissue of cabbage, and other vegetables. It also 
contains the products of some of the secretions, yellow biliary 
matter, intestinal mucus, and the crystals of uric acid and 
triple phosphate from urine. As in the last case, the living 
animal forms are numerous; and the vegetable growths are 
Oscillatoria, Confervae, Vegetable Spores, and numerous 
Fungi. The mineral part is composed of the dehrh of the 
streets, black sulphuret of iron, &c. 
