2. The Urea.-Mean amount of ureal excreted in twenty-four hours by adult males, between twenty and forty years of age. The number of days furnishing the mean in these analyses is generally more than six, often ten to twenty. The lowest amounts are placed at the top of the list:

Formula CH4NO3=C2O,"

Ha
H

viz., a diamine produced by the substitution No of the diatomic radicle carbonyl (CO2) for 2 eq. of H in diammonia (Hofmann).

With the exception of the analyses of Becquerel, Böcker, Lecanu, C. J. Lehmann, Scherer, and Rummel, all the analyses were made by the volumetric method of Liebig.

2 Die Wirkung des Nord-See Bades, 1855, p. 30.

3 Wurzburg Verhandlungen, Band iii, p. 184.

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

5 Henle's Zeits. für rat. Med., Band vii, p. 291.

6 Mean of all Böcker's numerous analyses. They are contained in so many periodicals, that it is impossible to give the references.

7 Valentin's Report on Phys., Canstatt's Jahresb. for 1855, p. 108.

Archiv des Vereins für wiss. Heilk., Band iil, p. 63.

9 Neubauer's Anleitung, 2d edition, 1855.

10 Scherer's Report on Phys. Chem., Canstatt's Jahresb., 1855, p. 206. 11 Harnstoff als Maass der Stoffwechsels, 1853.

12 Op. cit., p. 24.

13 Archiv des Vereins, Band iii.

The number of analyses included in this table is so great, that we may fairly assume we have got the limits of the range of the mean amount in persons of this age and sex, except in quite unusual cases.

The mean amount of urea excreted by different adult persons is therefore almost as variable as the amount of water, and one man may excrete nearly twice the quantity which passes from the body of another person of the same sex and age. The average of eight or ten days usually gives the amount proper to the individual. If the mode of life be kept very equable, the amount remains pretty constant from day to day; but then the greatest care is necessary to keep all physiological conditions even, and to choose periods of little atmospheric vicissitude.

It should be observed, that almost all the persons, the analyses of whose urine are given above, were living well, and were taking regular exercise.

The maximum and minimum amounts passed on any one day

1 Archiv des Vereins, Band iii, p. 431.

2 Wurzburg Verhandlungen, Band v.

3 Archiv des Vereins, Band iii, p. 627.

4 Mean of 30 observations on one person. Communicated to author.

5 American Journal of Med. Sc., April, 1859.

6 Op. cit.

Becher gives the amount as high as 47.20 grammes, or 728.7 grains (Ludwig's Phys. des Menschen, 1855, Band ii, p. 261). The observation appears, however, to be made on one day only, and I have therefore excluded it from the table.

Warnecke (quoted by Moore, Dublin Med. Press, July, 1859), found the mean excretion (mean of 7 days) of an adult man to be 33.7 grammes, or 520 grains, on mixed diet.

In a very interesting paper by the Rev. S. Haughton, F.R.S. (Dublin Journal, Aug. 1859), analyses are given of all the urinary ingredients. I have not included them, however, in the table, as they refer to only a single day's excretion. In SIX men on good meat diet, average age thirty-five, average weight 148 lbs., the urea amounted, on the mean of the whole, to 575-87 grains in 24 hours.

The analyses of Rummel and Scherer, quoted in the above, also refer to one and two days only.

by an individual are usually about one fifth above and below his mean amount. Thus, if the mean amount be 30 grammes in any person, the usual range is from 24 to 36 grammes, unless under unusual physiological conditions, such as large meat feeding, great exercise, &c.

The causes of the variation in the amounts on different days, in the same or different persons, are considered in the first chapter.' 3. Creatin.2 Creatinin.-The amount of these substances is not precisely known. Thudichum3 gives 0-305 grammes, or 4.7 grains, as the average amount of creatin, and 0.453 grammes, or 7 grains, of creatinin, in twenty-four hours. They are included under the head of "Extractives," in all analyses.

4. Urine pigment. Urohæmatin. Urophæin. The researches of Harley have somewhat modified the conclusions drawn from Scherer's researches, and seem to imply that there is only one pigment which has a very close relation to blood hæmatin, and contains iron. It is, however, variable in composition, and is easily decomposed; it then gives, as pointed out by Scherer, precipitates with basic and neutral acetate of blood. The amount of pigment excreted in twenty-four hours is not known, but it evidently composes a large part of the so-called "extractives." Whether, in addition, there is any substance capable of yielding pigment, especially blue pigment, or whether

1 It is possible that the variations from the mean amount are not so great in the persons passing a small quantity of urea as in those passing a large quantity; i. e., that the extreme range of a man passing 20 grammes a day may be only one fifth, viz. from 16 to 24 grammes, viz. 8 grammes a day; while the extreme range in a man passing 40 grammes may be one fourth, i. e., from 30 to 50 grammes in the day. But the analyses are not yet quite sufficient for decision on this point.

Creatin.
36.64

Creatinin.
42.48 per cent.

CH,N304+2HO
CH,N3O2

Formula-Creatin

Creatinin

3 Pathology of the Urine, 1858, p. 121 and p. 130. Mean of 26 days' observations on two individuals, aged each 28 years, and weighing 70 and 72 kilogrammes. * Composition (after Scherer), as far as analyses permit it to be stated:

Carbon
Hydrogen
Nitrogen
Oxygen.

5 Wurzburg Verhandl., Band v, p. 1.

Marcet (Comptes Rendus de la Société de Biologie, 1852, p. 57) was able to separate an acid from the pigment; and Harley found a resinous substance adhere so strongly to the pigment considered pure by Scherer, that it was very difficult to separate it.

urohæmatin itself will yield blue pigment, must be considered still uncertain. (See "Abnormal pigment.")

In analyses the pigment is included under the head of "Extractives."

5. Mean amount of Extractives in twenty-four hours.'—Under this head are included various substances, viz. pigment, creatin, creatinine, xanthin,2 hypoxanthin, sarcines (?), xanthoglobulin ; the resinous substances, called omichmyloxide by Scharling; the resin, discovered by Harley, which adheres so strongly to the pigment (perhaps the xanthin of Strahl and Lieberkühn); the acids discovered by Marcet; the substances containing sulphur and phosphorus, examined by Ronalds; and, perhaps, a little sugar (?).

The amount of the "extractives" excreted in twenty-four hours is not known with certainty, as the different substances cannot be isolated.

In four of Böcker's series, the amount of "volatile salts and extractives" was 16.038 grammes, or 247'6 grains. Scherer7 noted the quantity of "extractives and uric acid" to be 24-335 grammes, or 375-7 grains, in twenty-four hours, in a man aged

1 In order to avoid chemical details, which are easily accessible, I beg to refer to works on chemistry, and to Thudichum's work on the urine, for the composition of these substances.

2 Strahl and Lieberkühn, Harnsaure im Blut und einige neue Bestandtheile des Urin, 1847.

3 Strecker, the discoverer of sarkine in flesh, conjectures that it may pass into the urine, as it is a remarkably stable body; but it has not yet been isolated (Schmidt's Jahrb., 1858, No. i, p. 16). Scherer believes sarkine to be identical with xanthoglobulin.

4 Scherer (Canst. Jahresb. for 1857, Band i, p. 173) has discovered xanthoglobulin in normal human urine. Its constancy and amount are not known. 5 British and Foreign Med.-Chir. Rev., April, 1853.

• Philosophical Transactions, 1847, p. 461. Ronalds has stated that five healthy men passed in twenty-four hours the following amount of unoxidized sulphur, which probably was in organic combination, as sulphurets very seldom occur in the urine :

Griffiths (Medical Gazette, March, 1848) found 4 grains of sulphur in the urine of a healthy man.

Ronalds found in one case no less than 5.896 grains of unoxidized phosphorus. From an expression in Thudichum's work, I infer that he questions the accuracy of these analyses, but I am not acquainted with any experiments proving their incorrectness. Both Ronalds and Griffiths are quite trustworthy; and I may put as corroborative evidence a case of mine, of rheumatism (hereafter referred to), in which an amount of unoxydized sulphur was certainly present. In dogs, Bischoff and Voit have lately shown (Die Gesetze der Ernährung des Fleischfressers, p. 281) that a large quantity of sulphur is almost always present in the urine; and special observations by Voit on this point are promised.

7 Verhandl. des Phys.-Med. Gesellsch. zu Würzburg, Band iii, p. 180.

twenty-two; and 20.484 grammes, or 318 grains, in a man aged thirty-eight, and weighing 45 kilogrammes.

Rummel1 gives a much smaller amount of "extractives, mucus and uric acid," viz., 15.33 grammes, or 236-7 grains; and Becquerel's average for the "extractives" is even below this, viz., 11 grammes, or 180-6 grains.

If the volatile salts, uric acid, and mucus are deducted from the average of these various amounts, we obtain 15.31 grammes, or 236-3 grains, as the amount of the "extractives" in twentyfour hours. These numbers are, however, no doubt, much too high, and we may provisionally assume the true number to be about 10 grammes, or 154 grains.

6. Mucus.-The amount of mucus would appear, from Böcker's analyses, to be about 0.472 grammes, or 7 grains, in twenty-four hours.

Albumen.-It has been stated by Dr. Gigon, of Angoulême, that albumen exists in normal urine, and can be thrown down by chloroform. This has been denied by Becquerel, who considers the precipitate produced by chloroform in urine to be a mixture of chloroform, mucus, and organic substances. Gigon has reasserted his opinion, but there seems no doubt that Becquerel is correct. Aran has also made experiments adverse to Gigon's opinions.

Sugar.-Schunk 5 has shown that the pigment, when treated in a particular way, can yield sugar, or a body which decomposes the copper solution. Bruecke 6 has affirmed that, without any such decomposition, true sugar constantly exists in healthy urine. His experiments are altogether denied by Wiederhold 7 and by Lehmann,8 who has proved that Bruecke has mistaken uric acid for sugar. Boedeker9 has also stated that sugar is sometimes present, is sometimes absent. It is not an invariable constituent. There seems no doubt, however, that occasionally, and especially from a highly saccharine diet, small quantities of sugar pass into the urine; but it can scarcely be considered as a normal ingredient.

1 Verhandl. des Phys.-Med. Gesellsch. zu Wurzburg, Band v, p. 116.

2 Viz., 35 grains for the volatile salts, 8 grains for the uric acid, and 7 grains for the mucus.

3 Quoted by Scherer, in Canstatt's Jahresb. for 1858, Band i, p. 192.

4 Comptes Rendus, No. 21, Nov. 1857, and Gazette Médicale de Paris, 1857,

p. 772.

77.

5 Trans. of the Manchester Literary and Phil. Society, vol. xiv, p. 239. Bruecke, in Scherer's Report on Path. Chem., Canstatt's Jahresb. for 1858, p.

7 Deutsch Klinik, 1858, No. 46.

• Lehrbuch des phys. Chem., 2d edit., 1859, p. 140.

Henle's Zeitschrift für rat. Med., 1859, Band vii, p. 136.

10 Bischoff and Voit have noticed this also in the dog (Die Gesetze der Ernährung des Fleischfressers, p. 269).