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total quantity of urine for the fourteen days was 680 ounces; and the total quantity of faces 68 ounces.

The daily average was, urine 48 oz., fæces 5 oz., a greater disproportion than was anticipated, being nearly in the ratio of ten to one; they amount together to 534 oz. or 34 lb. nearly; but the quantity of food taken daily was 91 ounces; there remains a balance of 371⁄2 ounces to be accounted for, which must have been spent by the insensible perspiration from the skin, and that from the lungs conjointly, on the supposition that the weight of the body remained stationary.

I have already observed that the daily evacuations were not so nearly uniform as was the quantity of food. The urinary secretion was greatest when tea was substituted for milk, and on one day was 15 ounces above par. On another occasion, finding a greater defalcation than I had before observed, I could discover no cause for it, unless a tea-spoonful or two of vinegar taken at dinner could account for it. To be satisfied of it, I took, some days after, an ounce of vinegar in four equal portions during one day; and the effect was a greater diminution of urine on that day than on any other during the two weeks, the quantity being 15 ounces below the average, and 4 ounces less than the former day, when vinegar had been taken. There did not appear to be any increased effect in any other secretions, as a compensation for this diminution.

In order to try the effects of different seasons, I resumed these investigations in the month of June the same year, and continued them for one week successively. The results were what might have been anticipated nearly. A less consumption of solids, and a greater consumption of fluids, were observed. The evacuations were somewhat diminished, and the insensible perspiration. was increased.

The following were the results :

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being 4 ounces per day less in solids, and 3 ounces in fluids, than

in the former trial.

The daily averages in the evacuations were-urine 42 ounces; fæces 4 ounces, leaving a balance of nearly 44 ounces for the daily loss by perspiration, being an excess of about 6 ounces above that in the former season, or one-sixth more, owing no doubt to the higher temperature of the weather.

Another trial of one week's continuance was made in September the same year. The results were so nearly alike to those in June, as to render an enunciation of them unnecessary. The daily consumption of food was 93 ounces, and the perspiration one-half of that quantity.

I may now be allowed, perhaps, to subjoin one day's experience of the effect, that taking a large dose of carbonate of potash (salt of tartar) has upon the secretions. This was suggested by a similar experiment made by Dr Alexander, and published by him in a small volume of medical essays. His results I do not at present recollect; but my notes at the time imply, that I expected the alkali to act as a diuretic. My experiment was made on a fine day at the end of March after the two week series; the thermometer ranged from 40° to 60°. In the morning I had a basin of tea prepared for breakfast, with the usual quantity of sugar and cream; into this I infused 4 drams avoirdupois (100 grains) of dry carbonate of potash; after it was dissolved, I proceeded to my repast as usual, apprehending the diluted alkali would be so far qualified in its taste by the sugar, as to be rendered tolerably palatable, but in this I was mistaken; the nausea was unbearable, and I was obliged to drink it off as fast as I could, and then eat my toast to an additional cup in the ordinary way. This done, I felt nothing amiss, took a moderate walk, and returned. On sitting down, I perceived small drops of fluid on the backs of my hands, without any sensation of heat above common. My appetite was rather keener than usual during the day, and I felt uncommon agility in the evening. The secretion by the kidneys was not at all disturbed; but, on retiring to bed, I burst into profuse perspiration, which continued through the night, and was felt in degree during the succeeding night. By taking care, the effects went off without any detriment.

Being satisfied by the preceding trains of experiments, that no information was to be expected in this way, than was already VOL. XIV. NO. XXVII.-JANUARY 1833.

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acquired, I varied the process, with a view to obtain the quantity of perspiration, and the circumstances attending it more directly. I procured a weighing beam, by which I could weigh my own body, so that the beam would turn with one ounce. Dividing the day into periods of four hours in the forenoon, four or five hours in the afternoon, and nine in the night; or from ten o'clock at night to seven in the morning. I endeavoured to find the perspiration corresponding to those periods respectively.

My method of proceeding was, to weigh myself directly after breakfast, and again before dinner, observing neither to take or part with any thing during the interim, besides what was lost by insensible perspiration; the difference in the weights, in this case, was the loss by perspiration. The same procedure was adopted in the afternoon and in the night.

I continued this train of experiments for three weeks in November, the same year. I then took the aggregate of the morning observations, next that of the afternoon observations, and lastly, that of the night observations, and divided each of those three aggregates by the number of hours in the several periods, in order to find the hourly perspiration in each period, apprehending that there might be some differences owing to the time of the day, or being awake or in sleep.

The mean hourly losses by perspiration, were as under:

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During twelve days of this period, I kept an account of urine, corresponding in time with that of perspiration. The ratio was urine: perspiration 46: 33, or 7 to 5 nearly; which is somewhat greater disproportion than that observed in March; owing probably to the temperature of the weather being lower in the lat

ter season.

So far I have given the facts and observations made forty years since; I made no deductions from them at the time; indeed, the knowledge of animal and vegetable chemistry was at that time in its infancy. Since then, the progress of this branch of philosophy has been very considerable, and we are now enabled to approximate, in a good degree, to the quantities of the

several chemical elements to be found in the great variety of products of the two kingdoms.

By combining this knowledge with that obtained from the preceding facts, we may possibly discover or establish some physiological principles, important to be understood in the animal economy, more especially in regard to the acquisition and pre

servation of health.

From the table we have given, it will appear that bread and farinaceous vegetables constitute the greatest part of ordinary food. About the time of the above experiments, I found that 5 lbs. of flour would make 7 lbs. of bread. Now, from the analyses of flour that are given in our systems of Chemistry, I think we cannot estimate the carbon in flour at less than 42 per cent.; hence we have 30 per cent. of carbon in bread; 12 ounces of bread (the daily average in the first set of experiments) must then contain 3.6 ounces of carbon. Seven ounces of oatcake and oat-meal may be estimated, I think, = 1.8 ounces of carbon, or half the quantity that 12 ounces of bread have. Four ounces of pastry can scarcely contain less than 1 ounce of carbon. Nine ounces of potatoes must contain nearly 1 ounce of carbon. Four ounces of butchers' meat, and 2 ounces of cheese, would have together somewhere about 3 ounces of carbon, if Gay Lussac's experiments be nearly correct. Thirtyone ounces of milk, estimating the carbon at 3 per cent., gives eleven twelfths of an ounce. Twenty-two ounces of tea and beer would contain only a small fraction of an ounce of carbon, not easily estimated, but of little account, by reason of its small

ness.

From this, it would appear that about 11 ounces of the element carbon is taken into the stoinach by one kind of aliment or another, in the course of the day, in some state of combination.

Chemical analysis has been applied with considerable success to the animal product, urine. According to Berzelius, the urine of healthy persons differs materially according to circumstances. Upon the average it may be reckoned to consist of 93 or 94 per cent. of water, and the rest is a complication of a great many articles. The carbon contained in these ingredients cannot be estimated at more than 1 or 1 per cent. from the analysis hitherto made. This will give .5 or 6 of an ounce of carbon,

upon 481⁄2 of urine per day. Berzelius has not neglected the analysis of the fæces; of 100 parts, three-fourths may be estimated as water, and the rest do not seem to contain more than 10 parts of carbon. This would give half an ounce of carbon in 5 ounces. Hence we may infer that one ounce, a little more or less, of carbon, is carried off from the body daily through these two channels. The remainder, 104 ounces, must therefore be spent in the insensible perspiration.

The quantity of insensible perspiration from the skin, cannot be easily determined by direct experiment. That from the lungs may be approximated from known facts. I have shewn (See Manchester Memoirs, vol. ii. new series, page 27,) that I produced by breathing, in the space of twenty-four hours, 2.8 lbs. troy of carbonic acid gas. This is equivalent to .78 parts of 1 lb. troy of carbon = .642 parts of 1 lb. avoirdupois = 101 ounces nearly. Now, when I estimated the quantities of carbon in the several articles of food, &c. just related, I had no recollection of this quantity of carbon expended in breathing; it may be well supposed, then, that I was highly gratified to find by the calculation, that the difference of the two quantities, found by such different modes of investigation, was only a quarter of

an ounce.

With respect to the aqueous vapour exhaled from the lungs, I have determined, in the essay quoted above, (page 29) that the highest estimate of the quantity I exhale, cannot exceed 1.55 lbs. troy = 1.275 lbs. avoirdupois, = 20 ounces avoirdupois; if to this we add 10 ounces of carbon, we have 30 ounces for the carbon and water expended from the lungs in one day, and this taken from 37 leaves 62 ounces per day, for the insensible perspiration from the skin, which, if the above estimate be allowed, must consist of 6 ounces water, and one quarter of an ounce carbon. According to this, the matter perspired from the lungs is five times as much as that from the whole surface of the body.

If, instead of carbon, we trace the element azote into and out of the body, we shall find from our data, that from butchers' meat, cheese, and milk, about 1 ounce of azote is taken into the stomach daily, and nearly as much passed off by urine and fæces.

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