The Home Medical Library Volume V Part 4

More important still, there is an absolute need of the services of some expert on the ground. While an algologist is a functionary not generally employed by water companies--in fact, a man trained in the physiology of algae is difficult to find--nevertheless, it is highly important, as the department views it, to have the cooperation of an expert versed to some extent in the biological examination of drinking water. In other words, the copper cure is not a "patent medicine,"

with printed directions which any person could follow. Intelligence and care are absolutely essential in the use of this treatment.

Furthermore, each case must be treated as a distinct and separate case, as a physician would treat a patient.

_Actual Purification Simple_

Suppose, however, an owner of a country place, which is dependent upon a fresh-water pond for its water supply, finds that his drinking water is contaminated, that the taste and odor are such as to render the water unfit for use. There is no reason why he should not treat the supply, provided he is properly careful. When the nature of the polluting organism is definitely determined and the average temperature of the water observed, then the necessary formula can be decided upon. First, of course, the pond must be plotted, the depth found, and the capacity computed. The department will willingly furnish data for this purpose, together with blanks upon which to submit details as to contaminating organisms and water temperature, to any applicant. Once the proper solution is determined upon, the actual work of purification is most simple. In the following directions the department outlines the most practicable method of introducing the copper sulphate into a water supply:

_Directions for the Copper Cure_

"Place the required number of pounds of copper sulphate in a coa.r.s.e bag--gunny sack or some equally loose mesh--and, attaching this to the stern of a row-boat near the surface of the water, row slowly back and forth over the reservoir, on each trip keeping the boat within ten to twenty feet of the previous path. In this manner about a hundred pounds of copper sulphate can be distributed in one hour. By increasing the number of boats, and, in the case of deep reservoirs, hanging two or three bags to each boat, the treatment of even a large reservoir may be accomplished in from four to six hours. It is necessary, of course, to reduce as much as possible the time required for applying the copper, so that for immense supplies, with a capacity of several billion gallons, it would probably be desirable to use a launch, carrying long projecting spars to which could be attached bags containing several hundred pounds of copper sulphate.

"The subst.i.tution of wire netting for the gunny-sack bag allows a more rapid solution of the sulphate, and the time required for the introduction of the salt may thus be considerably reduced. It is best to select as warm a day for treatment as circ.u.mstances will permit."

_Cost of the Treatment_

Not difficult, one would say. No--when the proper solution is determined; to reach that determination is the difficulty. That the method can be tried "at home" is proved by the results obtained by the owner of a country home in the vicinity of New York. Tired of consulting engineers, who looked at his water supply, informed him that they could do nothing, and then charged him a big fee (to one he paid $250), this owner resorted to the copper-sulphate treatment. The cure cost the man just $2--but let his letter to the department tell the story:

"My place in the country is located at Water Mill, in the towns.h.i.+p of Southampton, in Long Island. I purchased it in April, 1902, and was largely influenced in selecting this piece of land by the beauty of a pond which bounds it on the east. This little body of water covers about two acres, is fed by numerous springs, and discharges into Mec.o.x Bay, the southern boundary of the land. When I bought the place the pond was filled with clear water. About the middle of the following June algae began to show, and in August the surface was almost entirely covered by the growth. The odor was offensive, and myriads of small insects hovered over the ma.s.ses of algae much of the time. I consulted two engineers interested in the storage of water, and they told me that nothing could be done. The condition was so objectionable that I planned to plant a thick hedge of willows along the bank to shut off the view of the pond from the house.... I examined the pond on June 15th and found large ma.s.ses of algae covering an area several hundred feet in length and from twenty to forty feet in width. No microscopical examination was made of the growth, but I was informed that it seemed to be largely composed of filaments of _Spirogyra_ and other _Confervae_. On June 18th the treatment was begun.... In one week the growth had sunk and the pond was clear water. I examined the pond September 15th and found it still clear.

"The use of the sulphate of copper converted an offensive insect-breeding pond into a body of beautifully clear water. The pond was full of fish, but the copper did not seem to harm them."

_Effect of Copper Sulphate on Fish_

Native trout were not injured when the large reservoir at Cambridge, N. Y., was purified by the copper treatment. A slightly different result, in this respect, was reported from Elmira, N. Y., however.

Part of the report is as follows:

"The effect of the copper-sulphate treatment on the different animal life was as follows: numerous 'pollywogs' killed, but no frogs; numerous small (less than two inches long) black ba.s.s and two large ones (eight inches long) killed; about ten large 'bullheads' were killed, but no small ones; numerous small (less than two inches long) 'sunfish' were killed, but no large ones.

"The wind brought the dead fish to the corners of the reservoir, and it was very little trouble to remove them. No dead fish were seen twenty-four hours after completion of the treatment."

The injury done by copper sulphate to fish is a more serious matter than was at first supposed. Brook trout are, apparently, the least resistant to the salt. A Ma.s.sachusetts trout pond stocked with eight-inch trout lost forty per cent as a result of the introduction of a strong solution of copper sulphate. The Bureau of Fisheries is working in conjunction with the Division of Plant Physiology in this matter, and it is hoped to secure reliable information. In the meantime, owners of ponds stocked with game fish would do well to take great care before resorting to the copper cure for algae--that is, if they hesitate to lose a part of the fish.

_Water May be Drunk During Treatment_

When a pond or reservoir is treated with the proper amount of copper sulphate to remove algae--except in the case of the few very resistant forms requiring a stronger solution than 1 part of copper to 1,000,000 parts of water--there is no need of discontinuing the use of the water supply during treatment; the water may be drunk with impunity. But when water known to be polluted with pathogenic bacteria is sterilized by means of copper sulphate in strong solution, it is just as well to discontinue the use of the water for drinking purposes for not more than twenty-four hours. Even then, this is an overcareful precaution rather than a necessity.

Experiments conducted with great care and thoroughness demonstrate that at room temperature, which is near the temperature of a reservoir in summer, a solution of 1 part of copper to 100,000 parts of water will destroy typhoid bacteria in from three to five hours. Similar experiments have proved that a copper solution of like strength is fatal to cholera germs in three hours, provided the temperature is above 20 F. As was the case with algae, bacteria were found to be much more sensitive to copper when polluting water than when grown in artificial media.

_The Use of Copper Tanks_

The toxic effect of metallic copper upon typhoid bacteria in water gives some hints as to prevention of the disease by the use of copper tanks. This should not altogether take the place of the boiling of the water; it is useful in keeping it free from contamination, although water allowed to stand in copper receptacles for a period of from twenty-four to forty-eight hours at room temperature would be effectively sterilized, no matter what its contamination and no matter how much matter it held in suspension. But in order to insure such results the copper must be kept thoroughly clean. This polis.h.i.+ng is not, as was popularly supposed, to protect the consumer from "copper poisoning," but to prevent the metal from becoming so coated with foreign substances that there is no contact of the copper with the water, hence no antiseptic quality.

Dr. Henry Kreamer, of Philadelphia, proved that within four hours typhoid germs were completely destroyed by the introduction into the polluted water of copper foil.

"Granting the efficiency of the boiling of water for domestic purposes, I believe that the copper-treated water is more natural and more healthful.... The intestinal bacteria, like colon and typhoid, are completely destroyed by placing clean copper foil in the water containing them.

"Pending the introduction of the copper treatment of water on a large scale, the householder may avail himself of a method for the purification of drinking water by the use of strips of copper foil about three and one-half inches square to each quart of water, this being allowed to stand overnight, or from six to eight hours at the ordinary temperature, and then the water drawn off or the copper foil removed."

Although a splendid antiseptic, copper in weak solution is not harmful, no more so than the old copper utensils used by our forefathers were harmful. Undoubtedly they were of benefit, and the use of them prevented the growth of typhoid and other bacteria. People of to-day might well go back to copper receptacles for drinking water.

FOOTNOTES:

[1] For published reports of the work, see Bulletins 64 and 76, Bureau of Plant Industry, U. S. Department of Agriculture; reports prepared by Dr. George T. Moore and his a.s.sistant, Mr. Karl F. Kellerman.

[2] See Bulletin No. 76, supra.

CHAPTER IV

=Ridding Stagnant Water of Mosquitoes=

Because of the serious and often fatal injury it inflicts on man, the most dangerous animal known is the mosquito. Compared with the evil done by the insect pest, the cobra's death toll is small. This venomous serpent is found only in hot countries, particularly in India, while mosquitoes know no favorite land or clime--unless it be Jersey. Arctic explorers complain of them. In Alaska, it is recorded by a scientist that "mosquitoes existed in countless millions, driving us to the verge of suicide or insanity." A traveler on the north sh.o.r.e of Lake Superior, when the snow was several feet deep, and the ice on the lake five feet in thickness, relates that "mosquitoes appeared in swarms, literally blackening the banks of snow in sheltered places."

_Mosquitoes Responsible for Yellow Fever_

In the temperate zone this evil-breeding insect was, until recent years, considered more in the light of an exasperating pest. It is now known, however, that malaria is due entirely to the bites of mosquitoes. But it is in the tropical countries that their deadliest work is done. There, it has been proved beyond question, the mosquitoes are responsible for the carriage of yellow fever. If, in a yellow-fever ridden region, one were to live entirely in an inclosure, carefully protected with proper screens--as certain entomologists did--there practically would be no danger from the dread disease, even if all other precautions were neglected.

_Effect of a Mosquito Bite_

The crime committed by the mosquito against its innocent victim, man, is more in the nature of manslaughter than of murder, according to the authorities. There is no _premeditated malice_. "A mosquito bites primarily to obtain food," says a leading entomologist; "there is neither malice nor venom in the intent, whatever there may be in the act." There isn't great comfort in the intelligence conveyed by the scientist, nor in his further observation:

"Theoretically, there would seem to be no reason why there should be any pain from the introduction of the minute lancets of the insects, and the small amount of bloodletting is usually a benefit rather than otherwise. Unfortunately, however, in its normal condition the human blood is too much inclined to clot to be taken unchanged into the mosquito stomach; hence, when the insect bites, a minute droplet of poison is introduced, whose function it is to thin out the fluid and make it more suitable for mosquito digestion. It is this poison that sets up the inflammation and produces the irritation or swelling....

The pain is caused entirely by the action of the poison in breaking up the blood, and, as the first act of a biting mosquito is to introduce the poison into the wound, the pain and inflammation will be the same, whether the insect gets its meal or not. In fact, it has been said that if a mosquito be allowed to suck its fill and then fly, the bite will not itch, and there is just a basis of justification for this."

To make a scientific inquiry into the habits of the mosquito, and to do it patiently, one should be far from the maddening swarms, or at least effectively screened in. Then it would be possible to believe the statement of the Government's entomologist that not "one mosquito in a million" ever gets the opportunity to taste the blood of a warm-blooded animal. As proof of this there are, in this country, great tracts of marshy land never frequented by warm-blooded animals, and in which mosquitoes are breeding in countless numbers. The point is emphasized by the prevalence of mosquitoes in the arctic circle and other uninhabited regions.

If this gory insect does not live by blood alone, how is it nourished?

Female mosquitoes are by nature vegetarians; they are plant feeders.

Why they should draw blood at all is a question which remains unsolved by entomologists--as well as by the suffering victims. The females have been observed sucking the nectar from flowers; obtaining nutriment from boiled potatoes, even from watermelon rinds, from which they extract the juice. As regards the blood habit, the male mosquito is a "teetotaler." Just how this male insect lives, scientists have not determined. He may not take nourishment at all. At any rate, the mouth parts of the male are so different from those of the female that it is probable his food is obtained differently. The male is often seen sipping at drops of water, and a taste for mola.s.ses is ascribed to the male mosquito by one authority.

_Presence of Mosquitoes Depends Upon Winds_

A common remark heard along the Jersey sh.o.r.e, also on Long Island, is this: "When we have a sea breeze we are not troubled with mosquitoes, but when there comes a land breeze they are a pest." While this observation is true, the reasons therefore entertained by the unscientific mind are erroneous. The matter of the absence or abundance of mosquitoes in varying winds is closely related to the inquiry which entomologists have made: how far will mosquitoes fly?

Says one investigator:

"The migration of mosquitoes has been the source of much misapprehension on the part of the public. The idea prevalent at our seaside resorts that a land breeze brings swarms of mosquitoes from far inland is based on the supposition that these insects are capable of long-sustained flight, and a certain amount of battling against the wind. This is an error. Mosquitoes are frail of wing; a light puff of breath will ill.u.s.trate this by hurling the helpless creature away, and it will not venture on the wing again for some time after finding a safe harbor. The prevalence of mosquitoes during a land breeze is easily explained. It is usually only during the lulls in the wind that Culex can fly. Generally on our coast a sea breeze means a stiff breeze, and during these mosquitoes will be found hovering on the leeward side of houses, sand dunes, and thick foliage.... While the strong breezes last, they will stick closely to these friendly shelters, though a cl.u.s.ter of houses may be but a few rods off, filled with unsuspecting mortals who imagine their tormentors are far inland over the salt meadows. But if the wind dies down, as it usually does when veering, out come swarms upon swarms of females intent upon satisfying their depraved taste for blood. This explains why they appear on the field of action almost immediately after the cessation of the strong breeze; on the supposition that they were blown inland, this sudden reappearance would be unaccountable."