Egg white contains about 1/100% of phosphorus, egg yolk about 1/2% estimated as phosphoric anhydride. Milk contains a little over 1 per mille of phosphorus.

Corn and oats contain very minute amounts of phosphorus but rice flour contains 2 - 3% and wheat flour about 1/2%, or about half of the total ash. Parsnips contain about 2:1000. Potatoes, ruta bagas and tomatoes about 1/2:1000; Figs, grapes, lemons, oranges, prunes, about the same. Almonds contain about 1%; chestnuts 1/2%, walnuts 3/4%. The legumes contain very little.

Mammalian brain contains about 2:1000 of phosphoric anhydride and muscle 3.5 - 5:1000, the latter figure being about the same as for fish.

As a very approximate estimate, it may be said that phosphorus thus estimated, amounts to about 1/2% of all solid food and that 1 - 2 kilos of solid food (not of organic nutrients) are eaten daily, so that the total phosphorus amounts to about 5 - 10 grams daily. Most of this is eliminated in the faeces as insoluble salts of calcium, and magnesium, the crystals of triple phosphate (am-monio-magnesium phosphate, being visible under the microscope in nearly every sample of faeces of alkaline reaction. About 3 grams of phosphoric anhydride are daily eliminated in the urine (as in other analogous cases, the precipitate being no guide to the amount, but quantitation by titration or centrifugal analysis being fairly easy). Whether it is necessary for health that this amount of phosphorus should be metabolized is not known but it is fair to assume that any great deviation should lead to a revision of the diet or may indicate some perversion of metabolism or elimination.

The phosphorus of vegetable tissues is largely contained in dense fibrous structures, and in insoluble form, so that it is extremely doubtful whether the less refined flours and meals really furnish less phosphorus for assimilation, than coarser flours and meals.

Sulphur. Like phosphorus, but to a less degree, sulphur plays both an inorganic and an organic role in the body, and is a constituent of many forms of albumin.

Fish contain about 1/2% of sulphuric anhydrid, the same as phosphoric anhydrid, but the limits are greater, up to 1 1/4% for smoked herring. Allowing for the relative dryness of fish, there is not so much fluctuation for either phosphorus or sulphur and the sum of the two (as anhvdrids) amounts usually to very nearly 1% of the total edible portion. There seems to be, however, no constant tendency to either direct or inverse relation of these two ingredients. As in the case of phosphorus, molluscs and crustaceans contain about the same amount of sulphur as fish, usually a little less.

So far as At water and Bryant's analyses go, most vegetable foods contain only 1:10- 1/2 as much sulphur as phosphorus. Onions, garlic, mustard and other plants mentioned as containing semi-medicinal principles, contain considerable sulphur in organic combination, as allyl sulphide, etc. Fibrin, egg albumin and casein are particularly rich in sulphur but sulphur is found in most proteins, to the amount of 0.3 - 2%. Hydrogen sulphid and carbon disulphid and aromatic sulphates are regularly formed in the intestine, mainly by the action of colon bacilli but sulphur-containing compounds are also end-products of tryptic digestion.

Corn, cauliflower, turnips and asparagus are mentioned by Thompson as especially rich in sulphates but at least part of the sulphur is in organic combination. Nervous tissues yield about 1 - 2 parts in 10,000 of sulphuric anhydrid. The commonly used meats of animals and fowls contain only traces of sulphur, horse meat a larger but still minute quantity.

The daily urine contains about 2 grams of sulphuric anhydrid, 1/10 of which is normally in the form of indican and allied ethereal sulphates derived from the intestine. Elemental sulphur is often administered in large doses without much influence upon the urine. Indeed, being somewhat antiseptic, it may even diminish the urinary sulphur by diminishing the ethereal sulphates.

It is obvious that sulphur is quantitatively less important than phosphorus and it is not certain that it is needed at all. At any rate, it is difficult to regulate the diet so as to increase or decrease its rather putative metabolism in the tissues. A very practical dietetic indication exists, however, to reduce the excessive production of sulphur-containing gases due to intestinal putrefaction, both by restricting germ activity and by omitting such foods as are rich in sulphur. As sulphuretted hydrogen precipitates iron, intestinal putrefaction is a cause of anaemia and the medicinal use of much larger quantities of inorganic iron than are needed in the tissues and blood, is of value to furnish iron with which this gas may combine. The occurrence of indicanuria to an excess, demands the control of intestinal saprophytosis, and the avoidance of proteins rich in sulphur or, indeed, of an excess of any form of protein. Hence, a diet mainly vegetarian (avoiding, however, vegetables rich in sulphur) acts in a double way in such cases.

Chlorine. This substance occurs mainlv as sodium chlorid and when, as is commonly the case, 20 - 30 grams or more are found in the urine not to mention elimination in the sweat and waste in the faeces, it must have been ingested largely as salt added in cooking foods or after they are served. About 10 grams of sodium chloric! are needed daily and this amount is present in an average, unsalted diet. .However, when the diet consists mainly of eggs, milk, and fresh vegetables, some salt is usually needed. Salt, artificially added is found in comparatively large quantities in preserved meats, cheese, canned foods, etc. Generally speaking, any natural food stuff contains the salt required to furnish the chlorine of hydrochloric needed for its digestion but it is empirically demonstrated that even the lower animals require additional salt as such, and that peoples to whom salt is not available by reason of inaccessibility of salt springs or the ocean or on account of taxation, formerly much practiced in Europe, suffer in health.

For practical purposes, the regulation of salt in the diet may be limited to salt as such and highly salted foods. It can always be sufficiently reduced by attention to these factors. To a large degree, a natural appetite is a safe guide. The amount of hydrochloric acid in the stomach contents and the amount of chlorids in the urine (which can be determined with sufficient accuracy for clinical purposes by Purdy's centrifugal method) should also be considered as guides to the use of salt, especially as perverted appetites are likely to be associated with perverted gastric secretion. The elimination of salt occurs very rapidly if an abundance of water is taken.

Iron. Most colored vegetables contain more or less iron, seldom more than 1 part in 10,000. Spinach is said to be especially rich in iron. Mammalian muscle contains 1/3 - 1 part in 1000, blood a trifle over 1:1000. According to various estimates, the human body contains a total of 3 - 7 grams and requires about 10 centigrams a day or about 1 ten thousandth of the total average ingestion of solids. It is probable that there can be no essential excess of iron in the system, although there is a physiologic provision for reserves in the liver, spleen, etc. Neither can an excess of organic iron in the alimentary tract be harmful. Thus, from the standpoint of dietetics, the indication is always in one direction, namely to increase the ingestion unless iron is introduced medicinally or as a gross contamination of food.

As has been intimated the major part of inorganic preparations of iron are precipitated by hydrosulphuric acid in the intestine or otherwise wasted; still it has been demonstrated that normal animals may assimilate inorganic iron. As a matter of fact, cases of anaemia very seldom recuperate iron with any degree of rapidity - excepting in anaemia due to haemorrhage - proportionate to the amount of iron taken, even if a large dose is given amounting to ten, twenty or thirty times the theoretic daily need. In other words, anaemia is not often due to iron starvation and recovery is as likely to take place without as with medicinal iron, providing that the diet contains a reasonable amount of meat, etc.

Acids. Vinegar, some wines and various fruits and their juices contain variable amounts of various organic acids. Although such acids are produced by fermentation, they are, in sufficient strength, antiseptic; indeed spontaneous fermentation is checked automatically when the acidity becomes sufficient to inhibit the saprophytes. Acetic acid of vinegar, citric acid of lemons and related fruits, lactic acid of buttermilk, are sufficiently strong to supplement hydrochloric acid in the stomach or more or less adequately to replace it. Buttermilk usually has an acidity of about 100% as estimated by decinormal alkali, or half as much again as normal gastric contents during digestion.

All of these acids are decomposed with the production of alkaline carbonates, so that the usual tendency is to lower the acidity of the blood and urine.

No systematic investigation of the nature and quantity of acids in food stuffs has been made and such analyses as have been made usually give neither the degrees by decinormal alkali nor the actual content of particular acids, but state the acidity in the equivalent of sulphuric acid or of some acid found in the fruit but not necessarily as the sole acid ingredient. In this sense, fairly tart fruits such as strawberries contain about 1% of acid, lemon juice about 7%, rhubarb 1/2%, cauliflower 0.6%, cucumbers 0.02%), egg plant 0.01%,.., potatoes 0.02%.

A great variety of organic acids are found in different fruits and these are, to some degree, mutually convertible in the stomach or even in the plant itself. Whether or not the introduction of such acids as acetic, malic, propionic, succinic, citric, lactic, etc., which are commonly found in fruits and vegetables, is at all comparable to the results of fermentation in the alimentary canal, with production of the same or closely related acids', is a very important question which has not been decided.

There seems to be no question that oxalic acid should be avoided as much as possible. (See list of oxalic-acid producers in consideration of Renal diseases). It is also to be seriously considered whether the results of gastric fermentation are not largely due to the formation of lactic acid from meats, milk, etc., and, if so, whether the free use of buttermilk, though temporarily bene-ficial may not have serious after-effects. Apparently oxalic acid may be derived from various organic acids present in fruit or formed by fermentation of carbohydrates. Hence it is often in excess in hypochlorhydria.

It is sometimes said that more persons have an idiosyncrasy toward strawberries than toward any other article of food but whether the erythema and urticaria are due to the acid or to some other ingredient has not been proved.

Generally speaking, highly acid drinks and fruits should be used in small quantities and not before meals. Otherwise, excepting oxalic acid and other harmful ingredients, sour vegetables and fruits may be used freely, according to appetite and individual experience, subject to limitation of indigestible and digestible ingredients within reasonable bounds. It seems 'probable that the increase of symptoms by an excessive use of sugars and starches in gout is due to fermentative changes culminating in the formation of an excess of oxalic acid.