A distinguished medical writer, Dr. Cheyne, remarking on the effects of foreign substances in water, states these facts:—
“At the Nottingham Assizes, July, 1836, it was proved on trial, at which I was a witness, that dysentery, in an aggravated form, was caused in cattle by the use of water contaminated with putrescent vegetable matter, produced by the refuse of a starch manufactory. The fish were destroyed, and all the animals that drank of this water became seriously ill, and many died. It was shown, also, that the mortality was in proportion to the quantity of starch made at different times, and that when the putrescent matter (of the manufactory) was not allowed to pass to the brook, the fish and frogs returned, and the mortality ceased among the cattle.”
Dr. Barry, an English physician, states, that when the troops at Cork were supplied with water from the river Lee, which, in passing through the city, is rendered unfit for drinking by the influx from sewers, Mr. Bell suspected that a dysentery, prevailing at the time, arose from this cause. Upon assuming the care of the troops, he had a number of water carts to bring water from a spring, and did not allow the use of river water, and very shortly the dysentery disappeared.
Sir James McGregor states, that, at one time in the Spanish war, when during three months 20,000 dead bodies were interred at Ciudad Rodrigo, all those exposed to emanations from the soil, and who were obliged to use water from sunken wells, were affected by low malignant fevers, or dysenteries.
This shows that burying in large towns affects the health of the inhabitants, first by emanations from the soil, and secondly by poisoning the water percolating through that soil.
Many such facts as these, show the importance of keeping wells and cisterns from the drainings of sinks, barn-yards, and from decayed dead animals. And it is probable that much sickness in families and communities has been caused by neglecting to preserve the water pure, that is used for drink and cooking.
Water is sometimes rendered unhealthful by being conducted through lead pipes, or kept in lead reservoirs, or vessels. It is found that the purer the water, the more easily it is affected by the lead through which it passes. When the water has certain neutral salts in it, they are deposited on the surface of the lead, and thus protect from its poisonous influence. Immersing a very bright piece of lead for some hours in water, will show whether it is safe to use lead in conducting the water. If the lead is tarnished, it proves that the water exerts a solvent power, and that it is unsafe to employ lead in carrying the water.
The continued use of water containing lead, gives rise to the lead cholic, or painter’s cholic, and if the water is still drank, palsy succeeds. One indication of this disease is a narrow leaden blue line on the edge of the gums of the front teeth.
The following are methods to be employed in purifying water:—
The most thorough and effectual way of obtaining perfectly pure water, from that which is noxious, is, to distill it, collecting only the steam.