solved in an extremely dilute condition through a vast volume of water; when it is directly acted upon by the oxygen in contact with the surface of flowing water, or artificially mingled with the air in tumbling over rocks and falls; when the oxidizing action thus produced is aided by the oxygen dissolved in the water and that which is liberated by the pores of aquatic plants, then this destruction is much accelerated. But this is not all. Light itself is a most powerful aid in increasing the rapidity of oxidation and in effecting these decompositions. Until the discovery of chlorine and bleaching powder, light was the only agency used to bring about an oxidation of the coloring matters in cotton and woolen goods, and thereby bleaching them. The same oxidizing action is taking place, aided by the chemical energy of sunlight, in the case of the matters dissolved in water, with the difference that the nitrogenous organic matter, which is the most objectionable part of this organic matter, is far more prone to decomposition and far easier of oxidation than the comparatively stable bodies which form the natural or artificial coloring matters of cotton and woolen goods.

"In the third place, aquatic plants and living organisms of unnumbered variety play a great part in altering, decomposing and assimilating organic and even mineral constituents in the water. Finally, clay and earth have an energetic attraction for ammoniacal compounds and nitrogenized organic substances. Every rain which washes into a stream finely divided earth, has a powerful influence in purifying and sweetening the water, because this mud in its precipitation carries down with it a large amount of organic material which it has removed from solution. The action is analogous to that of charcoal, which absorbs the noxious gases of water, and is able to remove from solution the strongest tinctorial substances, such as indigo. Indeed, the use of clay to remove sewage from water has been recognized in many patent processes of sewage precipitation. But what man does on a small scale and in a very crude manner, is done on a great scale and most perfectly by nature. The fact that lands periodically overflowed by river-water are so fertile, like the banks of the Nile, which have never lost their fertility, though longer cultivated perhaps than any part of the earth's surface, is due to the organic matter carried down by the finely divided mud, and not merely to ordinary organic matter, it should be remembered, but to ammoniacal and nitrogenized organic matter, such matter as is very easy to decay on the one hand, and very easily assimilated as nourishment by growing plants on the other. "I hold, therefore, that the statement so frequently made, that water once polluted by sewage cannot again become safe for drinking purposes after flowing any number of miles, is contrary to our common experience and observation. Furthermore, that the statement ignores the operation of natural agencies, the reality and efficacy of which are readily apparent. Finally, that wherever the pollution and subsequent self-purification of a flowing stream has been patiently

investigated, the chemical testimony as to the reality of this self-purification has been convincingly demonstrated.

"It is due to this process of self-purification, as I believe, that of the sewage of Paterson and Passaic a certain residue only remains at Avondale bridge. But each year this process is less adequate to deal with the increment of pollution, and each year the perils attendant upon the influx of sewage from above increased. The following is a recent analysis:

"The meaning of these figures is that the Newark sewage must be kept out of the Passaic, or the Passaic must be abandoned by both Newark and Jersey City as a source of water-supply. The grand jury of Hudson county has accordingly presented the mayor and corporation of Newark, for maintaining in the present sewage system Newark a nuisance, and it is upon the issue of this procedure that the future history of the water-supply depends."

of

In the discussion, allusion was made to the fact that in very large or deep reservoirs the lower water sometimes seems to become dead. It was suggested that there was interference with the vitality of the lower forms of bacterial life which were believed to conserve the purity of water. Not infrequently reservoir-water is not up to the quality of that in the river or source from which it comes. If so, even the water in stand-pipes need occasional comparison with that of the source. Pipes also vary in their supply. Professor Cook stated that just now two pipes in New Brunswick showed difference in supply which as yet was not accounted for. Changes that may occur in the inner surface of pipes must be studied. Sometimes these changes are such as impart taste or smell without any serious results. But we must seek to know the cause in order to determine whether it is casual and harmless or dangerous.

The subject of school hygiene was presented in papers by Professor H. B. Pierce, of New Brunswick; James Green, of Long Branch, and J. Madison Watson, of Elizabeth. Professor Pierce had been appointed the chairman of a committee with reference to resolutions

relating to school hygiene, which had been presented the former year. Already these resolutions had resulted in some valuable leaflets from the State Board of Health. Professor Pierce still urged the importance of compulsory ordinances as to contagious diseases, and for the prohibition of public funerals where there had been deaths from contagious disease; also that in all communicable diseases the notice should name the disease, so that those not wishing to attend, and especially children, might avoid exposure. While the value of these suggestions was recognized, Dr. Hunt, Dr. Newton and others expressed doubt as to the feasibility of including all these in compulsory legislation. Already the law gives authority to local Boards of Health, where they deem it necessary to the public health, to interdict public funerals and to require the notification of contagious disease. To compel local Boards to do this should not be the work of State legislation, unless in emergencies where the evil was spreading beyond localities and jeopardizing the State.

Professor Pierce again urged examination of teachers in the elementary principles of physiology and hygiene. The evils arising from long recesses and the advantages from calisthenics in the school room, and reliance upon very short recesses or individual permission, was again urged. The Association showed much interest in the views expressed and appointed a large Committee of Conference, with power to act by way of recommendation to the Legislature or to School Boards.

The substance of Principal Green's paper will appear in this report.

That of Professor J. Madison Watson will be in the ninth volume of the American Public Health Association.

Professor C. F. Brackett, of Princeton, explained such appliances for the raising and distribution of water as are of more recent application. In Manchester, N. H., the source of supply has been made to furnish the power by water-wheels and pumps much above the source. By another contrivance, a bucket, automatically filled, is made to work a pump-plunger in connection with a counter-weight so as to supply water from a small stream to a number of houses. Solar heat has been applied so as to work an engine and pump, and raise water from driven wells. By the use of electricity as a transmitter of power over long distances, the sewage of a city situated in a valley entirely surrounded by hills, may be made to run dynamos, drive waterwheels and so transfer power to a pumping station as to raise sewage or water over ascents where drainage and tunneling would be impracticable.

Air tends to

In that distribution, which needs to take place after water has become the vehicle of organic matter in suspension or solution, as in the ordinary sewer-pipe, he illustrated the advantage of a running stream constantly fed with air at every possible point. adhere to surfaces and to water and to mingle with it. If, from the upper segment of the pipe, there go up wherever possible small tubes for admission of air, and if these tubes reach down so as to go into the flowing stream, there will be a constant adherence or drawing in of air which thus mingles with the water and performs its oxidizing and purifying processes with remarkable rapidity.

The subject of filtration was treated by Professor Geo. H. Cook, of New Brunswick. Its contents will be found in this or a subsequent report. These selections from the meetings of this Association thus present an index of the broad field of sanitary science and art, and contain very valuable suggestions for the people of the State. Physicians, engineers, chemists, teachers and the workers in the practical details of mechanics find these conferences of great value and are thus contributing to the social, household and economic welfare of the State.

TRADES AND OCCUPATIONS.

BY EZRA M. HUNT, M.D., SECRETARY.

The relation which an inquiry into trades and occupations has to public health and welfare has been recognized from the first conception and application of sanitary art.

It first became apparent in an inquiry as to poor laws and the effect of friendly societies, because it has so often found that penury or sickness had resulted from the effects of trades or from the conditions under which they were followed.

The first official appointment in England that can be said dis-. tinctly to have had its origin from the writings and appeals of sanitarians, was that made in 1832, when Dr. T. Southwood Smith, Mr. Thomas Tooke and Edwin Chadwick were appointed to investigate the question of factory labor.

The prosperity of a country and the welfare of the population are very dependent upon the various trades and occupations and consequently upon the health of the operatives.

There are various reasons why so important a public concern cannot be left to self-regulation. The multitudes of workmen, as well as their employers, are ignorant of some of the necessities of physical life and of the special complications and embarrassments of various ecupations. The harm done is often gradual and is not realized until well nigh irremediable.

Most, even, if feeling the embarrassments to which they are exposed, do not know how to ameliorate or avoid them, or, if they do, cannot enforce the provision of and compliance with the needed adjustments. First of all there is need that there be a better understanding on of all of the demands of life and health and the conditions and surroundings which are most favorable thereto.

the

part

Next to this is a knowledge of the real evils and how to counteract

or correct them.

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