distilled water. Both samples are then inspected. The distilled water is of a pale blue tint; a yellow or brown color of the water that is being tested will show that it is polluted with organic matter and should at once be condemned until submitted to a thorough analysis. Again, by pouring the water into a wide-mouthed bottle and shaking well, then placing it in the rays of the sun or in a warm place, if an unpleasant odor arises it should be condemned; by placing it over a spirit lamp, shaking well and adding a little caustic potash while the water is still warm, then if an unpleasant odor arises. it shows that it contains organic impurities, and if there is a white precipitate it shows the presence of lime and magnesia which all hard waters contain. Again, if a water is suspected of containing organic matter it can be tested with a solution of permanganate potash; take a glass of the suspected water, add one or two drops of the solution, and if there is organic matter the coloring of the solution will be destroyed immediately, the oxygen in the solution destroying the organic matter contained in the water, disorganizing the solution of permangan

ate.

Drinking water most to be dreaded is that impregnated with sewage, and the characteristic features of sewage are large quantities of organic matter, nitrogenous compounds being the most dangerous. The substances contained in water are aids to determining its quality, and are usually of the following: organic carbons, organic nitrogens, suspended matter, ammonia free and albuminoid, nitrogen in nitrates, and nitrites, and chlorides. Observations may also be made on the color, odor, taste as I have said before, and especially the source-spring, well, pond or river-and the surroundings noted. It is an accepted fact that water containing nitrogenous organic matter affords by putrefactive decomposition ammonia, then of nitrites and lastly of nitrates. The changes do not take place at once, when water has taken up organic matters, in the first stages of decomposition ammonia and al

buminoid ammonia are prominent, and later on, by contact with earthy matter, nitrates and nitrites are found, and the change is thought to be caused by a ferment in earthy matter in which it comes in contact; so water that has percolated through the soil into a well we can safely say almost always contains these compounds, while water that contains immediate sewage has none or but little. Well water is the most dan

gerous of all; it may be contaminated to a dangerous extent and still have the appearance of wholesome water, be clear and sparkling and still be loaded with the nitrates and nitrites and their compounds. These compounds cause water to look clear and sparkling, and as they are formed by contact or by percolation through the earth, wells are the most likely to contain them. These compounds are not very frequent in water that is used for domestic purposes, but their presence even in small quantities is regarded as a dangerous indication. Nitrogen as nitrates is a common constituent in water, and is not harmful if derived from soil in which there is much chalky matter, and when testing for these compounds the sanitary officer should know from whence these compounds are derived. Water that is derived from a formation composed of chalky elements will contain nitrogen as nitrates. and nitrites. These compounds, the most to be feared, are the ones derived from the decomposition of animal organic matter, vegetable matters yielding but mere traces. When these compounds are suspected, the water should be sent to a competent chemist. The officer can usually tell if they are present by testing for ammonia (albuminoid ammonia), which is the first formed by the decomposition of the nitrogenous matters, the nitrates and nitrites forming later taking an alkaline solution of potassium permanganate with which distillation ammonia is formed, which can be easily detected by its odor, or Nessler's reagent, a double iodide of potassium and mercury added to the water and distilling the same, adding first an alkaline solution to neutralize the salts of lime and mag

nesia and sulphide which interfere with the test. The ammonia is carried off in the steam in the distillation in the form of free ammonia.

In villages where the people get their water from a common well or private ones, the water often becomes contaminated through cesspools or privies, and the most convenient way of ascertaining whether any contamination exists through connections, especially so if the ground is sandy or of a gravelly nature, is by putting into the cesspool or privy some solution, such as carbolic acid, which would be readily tasted, or any other solution and testing for it. In one of the British barracks in India the garrison were smitten with typhoid fever. The drinking water was not suspected, but a solution of carbolic acid was mixed with the contents of a large cesspool, and in a few days it was tasted in the water, to their surprise, and the well condemned.

Prof. Church gives an account, in "Plain Words about Water," of a well in a small town in England, which suddenly dried up without any apparent cause. It was found that one of his neighbors had had a water closet close by, but had taken it out, substituting an earth closet in its place, thereby cutting off the water supply. I simply mention this to show how water can percolate through the earth.

In order to make a microscopical examination of suspected water, the water should be allowed to stand for some hours, or until all the sediment has settled to the bottom of the vessel used; then removing with a pipette, the sediment can be examined under a microscope. Textile fibers, hair, and other debris should be looked at with suspicion, because they are indicative of sewer pollution; wood fiber and vegetable tissue are easily recognized under the microscope.

The biological examination of water is for the purpose of telling the kind and character of organisms found in water.' Water fleas can be seen with the eye, and are usually found in good water, because they can not exist in water contam

inated with sewage. Vegetable forms, such as desmids, dia

tornes, oscillatoria, and bacteria are found in water that has been exposed to the sun, or light, and never found in closed wells.

Microbes are always found in natural water, even in the best of springs, and their number increases in proportion to the impurity of the water. They are discovered best by cultivation, gelatine being used as a medium, when the colonies can be counted. A great number of these microbes are inert and the difficulty arises to tell which are harmful and which are not. The results so far obtained by biological examination, it must be admitted, have not been of great value to the physician on account of the difficulty of distinguishing the disease-producing germs from the harmless ones. But if the science of microscopy develops in the future as it has done in the past, pathogenic germs will be easily distinguished from their inert neighbors.

I am not attempting to give a thorough analysis of water, but simply to point out to health officers of local boards how they can detect in water elements which they know will produce disease, rather than have them go on for months at a time when they know that typhoid fever is in their midst, without ascertaining at once whether it is the water or not that is producing the disease. There are about 1,200 local boards of health in our State, and each board has its health officer who is supposed to be able to acquaint them at any time in regard to the condition of the water used.

The State Board of Health has made arrangements with the State chemist and biologist to have all public waters analyzed when suspected of containing elements that will produce disease. If this procedure is only followed, as it should be, and all dangerous water condemned, the time is not far distant when the last case of typhoid fever will have made its appearance in this State.

THE ADVANTAGES OF THE USE OF Deep unDERGROUND WATERS FOR HOUSEHOLD

PURPOSES.

BY PROF. C. R. VAN HISE, OF MADISON.

The advantages of the use of deep underground waters for household purposes are so obvious that I have decided to speak upon the resources of the State of 'Wisconsin in that regard. By previous speakers it has been explained that a small thickness of sand and gravel is sufficient to remove a large part of the organic matter which may be in surface waters and that a considerable thickness of such material is sufficient to remove all of the organic material. It is therefore obvious that deep underground waters are freer from danger of contamination from organic sources than any other available water supplies, such as lakes, rivers, or shallow wells.

Now it so happens the State of Wisconsin is so constructed that over a large part of it underground waters can be drawn upon for household purposes. The amount is adequate to supply farm houses, to supply villages, to supply cities of considerable size, all cities of the State, in fact, except those of the first class. The area in which there is an abundant supply of underground water is indicated on this map of the State of Wisconsin (Plate I of the Atlas of the Geology of Wis., Report of Wis. State Survey for 1881). The area is roughly U-shaped; it includes a broad area in the eastern part of the State, extends over a large portion of the southern part of the State, and thence swings northwest along the Mississippi river. It is noticeable that this is the area that is most densely populated. Upon it lives a large majority of our population.

The water-bearing strata which are available for deep underground water in this part of the State are two in number,

27-S. M.S.