INTRODUCTION.

SECTION I.

ON THE AVERAGE QUANTITIES OF THE NORMAL CONSTITUENTS

OF THE URINE, EXCRETED BY HEALTHY MEN, BETWEEN
TWENTY AND FORTY YEARS OF AGE, IN TWENTY-FOUR
HOURS.

FOUR methods have been, and in part are still, employed in stating the composition of the Urine.

First. In most of the older analyses, those, for example, of Simon and of his pupil Heller, the per-centage amounts of the urinary constituents are alone determined, i.e., it is stated that in 100 or 1000 parts of urine there are so many parts of urea, uric acid, salts, water, &c. Such analyses give only the relative amounts of the constituents inter se-information of comparatively little value.

Second. In order to eliminate from the analyses the differences caused by the ever-varying amounts of water which are excreted from the kidneys, the per-centage amounts of the solid constituents of the urine are given in many analyses, and it is stated that, in 100 or 1000 parts of the dried solids of the urine, there are so many parts of urea, uric acid, salts, &c. This plan, like the former, gives only the relative amounts of the constituents inter se, and is, in fact, merely a more accurate method of stating the same facts.

Third. As it was soon seen that no deductions of any value could be drawn from the employment of these plans, a third method of stating the results of the analyses has been adopted, and the amounts of the urinary constituents, formed in, and excreted from, the body in a given time, have been determined. This method gives not only the relative but the absolute quantities of the constituents, and it is now in general use. The

period of twenty-four hours is usually chosen (unless under special circumstances), as in this time the body passes through the entire cycle of changes caused by exercise, rest, sleep, food, day and night, &c.

Fourth. The results of the analyses are often stated not only in relation to the time during which the constituents were formed, but in relation also to the amount of weight of the body. Thus, in addition to saying that so many grains of urea or uric acid were excreted in one, twelve, or twenty-four hours, it is also often stated how many grains were furnished by each pound weight of the body in the given time.1

As these two last methods include all that is valuable in the other statements, they have been alone employed in the following work; and this introduction is chiefly occupied with an enumeration of the mean amounts of the urinary constituents excreted in twenty-four hours by the whole body, and by a definite amount of body weight in adult males.

In this Introduction I have collected together, from all sources, as many analyses as possible of the various urinary constituents in perfectly healthy persons, and have taken the mean results arrived at by each observer. These mean results have been, in almost all cases, derived from the investigation of many days; in a few cases only I have taken the mean of so small a number as three days. Almost always the number of days has been sufficient to give the true mean proper to the particular individual experimented upon.

In order to obtain a standard with which other analyses might be compared, I have selected the male sex, and the period of life between twenty and forty years.2 The variations from this standard produced by sex, age, food, exercise, &c., are afterwards considered in the body of the work.

The analyses are taken from French, German, American, and English sources, as in all these countries the mode of life is sufficiently alike to allow of a comparison. The quantities are given both in French and English weights, for the convenience of the reader. The gramme is taken as 15:44 grains, and the cubic centimeter as 16.9 minims. The nation of the observer is sufficiently indicated by the name and the reference. The food was in all cases sufficient and of good quality.

1. The Water of the Urine.-Average amount of urine passed in twenty-four hours by healthy male adults, between twenty and forty years of age. The number of days furnishing the mean is in no case less than six, and generally many more

1 The excretion in a given time, according to the height of the body, is sometimes used, but at present no value attaches to these determinations.

2 In one case the age was eighteen, and in one case a little over forty.

than this. The lowest numbers are placed at the top of the list:

1 Canstatt's Jahresb., 1857, Band i, p. 84.

2 American Journal of Med. Sci., April, 1856.

3 Mean of 20 days in one person.

4 Semiotique des Urines, 1841.

Journal de Pharmacie, 1839, t. xxv, p. 681.

• Edinburgh Medical Journal, 1860.

7 Valentin's Report on Phys. in Canstatt's Jahr., 1855.

Unters. über den Einfluss des Wassertrinkens. Wiesb., 1856, p. 68.

9 Vierordt's Archiv for 1856, p. 555.

10 Various papers in the Archiv für wiss. Heilkunde, and Die Wirkung des Nord-See Bades, 1855. (Mean of all the experiments on the same person.)

11 Archiv für wiss. Heilk., Band iii, p. 63.

12 Archiv für wiss. Heilk., Band iii, p. 627.

13 Die Harnstoff als Maass des Stoffwechsels, 1858.

14 Quoted by Moos., Henle's Zeitschrift für rat. Med., Band 7.

15 Archiv für wiss. Heilk., Band i, and Neubauer's Anleitung, 2d edition.

16 Ueber die Harn, &c. Aus., Nova Acta, Band 25, 1856. (Beigel's calculation is wrong; his mean number is really 1708, but I have quoted his printed number, as the difference is slight, for fear of confusion.)

The mean amount of water excreted through the kidneys by different male adults is, therefore, remarkably diverse. One man may excrete, on an average of ten days, only 35 fluid ounces a day; another, 81 fluid ounces. The causes of this difference are stated under the different headings in the first chapter, but may be said, in general terms, to depend, 1st, on the varying quantity of water passing in; 2d, on the varying quantity passing off by the other organs (the skin, lungs, and bowels), which eliminate water; and, perhaps, 3dly, on the varying amount of water formed in the body.

In the same individual the variations from his mean amount i.e., the maximum and the minimum quantity he may pass on any one day, have a considerable range, which, in round numbers, may be said to be about one fourth of the mean amount above and below the mean amount.4 For example, if a man passes forty ounces on an average of ten or twenty days, he will be found to pass in that ten days, sometimes 30 ounces, sometimes 50 ounces, or numbers between these amounts. Occasionally, under special physiological conditions, as when the skin is very active or inactive, when much fluid is taken, or the reverse, the range may be even greater than this; but it appears that, as a rule, in the absence of any powerful physiological condition, a man seldom passes, for two days together, an amount which is very greatly above or below the limits of the range proper to him. If he does do so, some pathological condition is generally present.

1 Phys. Chemie, 2d edition.

2 Mean of 30 observations on one person, communicated to author.

3 Beiträge zur Heilkunde, 1849, and in numerous periodicals (mean of the whole on the same person).

4 In my own case the range is exactly one fifth, the lowest amount (the mode of life being equable) is 32 ounces, the highest 48, and the mean exactly between the two, viz. 40. But in other persons the range is more, and in some cases it may be as much as one third; but the usual amount is one fourth.