The management of diet is of the greatest importance for the prevention of the formation of renal calculi. These stones may be composed of uric acid, of oxalic acid, of the phosphates, or of two or all of these ingredients and much less frequently of other organic substances. Each variety requires an especial regimen.

Calculi vary in size from almost microscopic crystals and fine sand to stones of large size. The former usually occurs as crystals of one kind, the latter as agglomerations of one or more kinds of crystals or of amorphous chemical substances. Calculi are often laminated, each layer consisting of a different substance. The recent analyses of stones removed from the kidneys and bladder by Benjamin Moore1 show that they consist commonly of a mixture of calcium oxalate, calcium phosphate, and uric acid. Of these ingredients the former occurs in much the largest amount.

Uric acid calculi are due to a persistent excess of uric acid in the blood and to an acid condition of the urine. The excessive, or sometimes the generous, use of nitrogenous food will cause both of these conditions. Necessarily, therefore, meats must be used sparingly by those liable to the formation of uric acid stones. It is usually possible for such patients to eat eggs, fish, oysters, and clams with safety. Even the red meats may be eaten, but in moderation, and not oftener than once a day. Other foods may be used as they are relished, provided that the stomach or the organs of digestion are not overtaxed. Indigestion ought to be prevented in every way possible. Water should be drunk copiously, not only in order to stimulate elimination by the kidneys, but also because drinking freely dilutes the salts of the blood and in that way helps to prevent their deposition in the kidneys. Inasmuch as water that is as free from mineral matter as possible is the best, distilled water or pure soft waters, such as the spring waters of Waukesha, which contain a minimum amount of salts, are to be preferred. The lithium waters, too, are often prescribed. The generous consumption of all these waters is beneficial, but all recent investigations show the inutility of lithium in these cases. It is true that the lithium compounds of uric acid are readily soluble and eliminable, but they are not formed in the blood when lithium is taken into the stomach. It forms in that organ very stable compounds with phosphoric acid, which are not decomposed in the blood. Saline waters, such as come from the Vichy and Geyser Springs of Saratoga, and from Vichy, Vals, and Kissingen Springs of Europe, are often used with advantage by those who have indigestion. The stronger saline waters, such as can be obtained at West Baden springs in Indiana, Congress and Hathorn Springs of Saratoga, and at Carlsbad in Bohemia, are useful for the same class of patients, especially when the latter are stout. But these saline waters should not be recommended to those who are weak, neurasthenic, or anemic.

1 British Medical Journal, April 1, 1911.

A residence at a spa is advantageous because of the change of scene, of food, and of mode of life that it insures. The freedom from care and continuous work, and the outdoor exercise incidental to it are often important elements of cure, aside from the fact that more water is drunk there than at home.

Moderate, regular exercise in the open air is necessary to promote good digestion and assimilation. Hot baths and friction of the skin are advantageous for the same reason. The use of alcoholic beverages should be forbidden.

Oxalic acid calculi are caused by eating vegetable foods rich in this acid, which must consequently be forbidden. The commonest articles containing oxalic acid are rhubarb, sorrel, tomatoes, tea, spinach, cabbage, and celery. The use of the following vegetables and fruits is also prohibited by some clinicians: turnips, onions, apples, pears.

Indigestion is as essential for the formation of these calculi as the presence in the stomach of food containing oxalic acid. Indeed, it is claimed by some chemists that bacteria can produce the acid out of sugar, starch, and cellulose. Prevention and correction of indigestion are more important to effect a cure than the withdrawal of the foods just named from patient's dietary.

Only simply cooked food should be eaten. Animal foods, dry bread, and milk should form the staple articles of diet. Fats and fried foods should be avoided; tea, coffee, and alcoholic beverages likewise. Water ought to be used with the same freedom as in cases of uric acid calculi, one and a half or two quarts of liquid being drunk daily. What has already been said of mineral waters and a residence at springs for those suffering from uric acid calculi is applicable also to these cases. Exercise and an out-of-door life, and freedom from anxiety and care are equally necessary to success of treatment. The character of the digestive disorders that underlie the ailment usually affords indications that govern the details of treatment.

Phosphaturia will occur only when the urine is persistently alkaline or nearly so. As a vegetable diet is most likely to cause this condition, a diet consisting chiefly of meats, breads, cereals, and milk is to be preferred. Water is quite as necessary as in other varieties of renal calculi. Chronic cystitis and pyelitis which commonly produce alkaline fermentation in the bladder or renal pelvis are especially apt to be accompanied by the formation of phosphatic calculi. When these conditions exist they must be corrected by appropriate treatment.

As lime forms the base of many calculi it is also important to forbid the use of beverages and food containing it in large amounts. Hard water, milk and milk products are the commonest sources of this element in any considerable quantity. Therefore hard water should be forbidden and milk and milk products should be eaten abstemiously.

Such hygienic and dietetic directions as have been prescribed for these cases usually will not effect the removal of large calculi, but they will prevent the formation of new stones or the enlargement of old ones. Drinking water very copiously will often effect the removal of fine crystals, or renal sand, as they are sometimes called, from the pelves of the kidneys.

When renal colic is caused, opiates and anesthetics must be employed to relieve the pain. In the mildest cases rest, counterirritants, or hot applications are helpful, and are, indeed, sufficient to bring about a cure in some instances.