containing plenty of salt may secrete a very small amount of chlorine during the sleep of the night following, and for breakfast may take food containing no addition of salt, or no food at all, or only a tumbler-full of water, yet the amount of chlorine discharged during the hours of the forenoon, when the mind and body are most active, and when the nutritive changes of the body are being rapidly effected, will be double the amount of that during the night. It will of course rise still more, if food containing an addition of salt be taken. The amount of chlorine discharged after a substantial English breakfast, with meat and eggs, is therefore considerably larger than that discharged after the Continental café au lait, or the coffee and hot rolls of the German student. Hegar found that a person who used to be given to mental labour discharged more chlorine per hour of the night (0.47 grammes) than during the same time in the morning, when the quantity was only 044 grammes. Vogel observed frequently an instantaneous increase in the amount of chlorine secreted by the urine under the influence of increased mental and bodily labour. We have already seen that the same causes exert a similar influence upon the total quantity of urine discharged, and upon the amount of urea secreted with it. There can be no doubt that most of the ingredients of the urine share this fate, as we have seen or shall see more particularly under the history of the single substances. Vogel states, moreover, that by the ingestion into the system of large quantities of water, which stimulate the kidneys, not only the amount of urine and urea, but also of chlorine is increased. After the stimulus has ceased, there follows a period of relaxation; during which the activity of the kidneys becomes lessened, and less chlorine than usual is excreted. A person whose hourly secretion of chlorine during the night was 0.13 grammes, drank four pints of water in the evening. The hourly amount of chlorine rose to 0·60 for several hours, fell then to 0.12 grammes, and somewhat later to 0.10 grammes. In the morning, however, though no breakfast had been taken, the amount of chlorine was raised to 0.51 grammes by horse exercise. Another person drank four pints of water in the afternoon after dinner, whereby the hourly amount of chlorine towards and during the evening rose to 1-89 grammes; during the night it amounted to 0.57 grammes, being 019 in excess of the usual average. On the next morning the same individual drank again two pints of water; but, notwithstanding this, the hourly amount of chlorine remained below the normal average during the

entire day, amounting only to 0-42 grammes, sinking in the night following as low as to 0.014, rising a little on the second morning to 0.22 grammes, and falling again to 0.18 grammes, notwithstanding the person had eaten a piece of bread and butter with much salt (vide Vogel, p. 257).

Upon the basis of the above facts we are now enabled to explain the opinion of Barral,1 who by a series of very accurate analyses, the substance of which was first presented to the French Academy, and subsequently published in a separate form, came to the conclusion that chloride of sodium increased the elimination of the nitrogenized ingredients of the urine. In some of his experiments, Barral determined the whole amount of chlorine taken with the food, and, on the other hand, the chlorine and urea excreted. If such a series of analyses were now to be performed by the more accurate methods, there can be no doubt that they would lead to important evidence regarding the causes and influences determining and modifying the amount of chlorine excreted by the kidneys, particularly if the fæces and other excreta were also taken into consideration. There is one way, however, in which chloride of sodium indirectly increases the discharge of urine and its ingredients; namely, by causing thirst when taken in any quantity; the water which is drank in consequence, acting as a stimulant of the kidneys, carries away, not only the salt, but also organic ingredients in solution.

Chlorine of the Urine in disease.

Since Redtenbacher drew the attention of the medical world to the fact of the absence of the chlorides from the urine discharged by patients in certain stages of pneumonia, and to the diminution of these salts in other stages of that disease, many researches have been made in that direction. Though at first they were mainly directed towards pueumonia, of which disease exclusively the absence of the chlorides was for some time thought to be a peculiar feature, yet the extension of the investigations to other diseases showed soon that the bearing of the chlorides in all acute diseases was so very much the same, that the idea of its being a peculiarity of pneumonia had to be abandoned.

The result of many observations of Vogel and others, last of myself, then, is that in all acute febrile diseases the

1 Barral, S. A., 'Statique chimique des Animaux, appliquée specialement à la question du sel,' Paris, 1850.

2 Beale, Dr. Lionel, 'Med.-Chir. Transact.'

amount of chlorine discharged in the urine sinks rapidly to a minimum, say one hundredth part of the quantity normal to the individual, until at last, in certain cases, it disappears entirely for a short time. When the diseased action is abating, the amount of the chlorides rises during convalescence, sometimes above the normal average. We have already seen that the total quantity of urine has a similar relation to the stages of acute febrile diseases. But it is the reverse with the colouring matter or uræmatine, the amount of which rises and falls in the inverse ratio of the chlorine; so that when the latter is entirely absent, the former is discharged in the largest quantity. Urea, on the other hand, though rising at first in amount inversely to the sinking of the amount of chlorine, afterwards sinks below the healthy average, and during convalescence rises parallel with the amount of chlorine.

In the case of a man suffering from severe pleuro-pneumonia, Vogel found the chlorine sinking rapidly to 06 grammes in twenty-four hours on the third day of the disease, to 0:3 grammes on the fourth, on the fifth to almost 0. From this day the discased action abated, and the appetite improved, when, together with these improvements, the amount of chlorine discharged rose to the normal average, as the following figures show: 04, 18, 26, 55, 90 grammes. From this time the amount of chlorine fluctuated a little, and sometimes exceeded the normal average. It was, on the respective days, 107, 13·5, 97, 119, 159, 108 grammes.

The same course has been established by the observations of Beale. He found that the chloride of sodium was totally absent from the urine of pneumonic patients at the period of complete hepatization of the lung, and that it reappeared after the resolution of the inflammation. The fact that the sputa of pneumonic patients contain a very large quantity of the chlorides, must probably be explained by their being in part extravasations and exudations from the blood, which, we now know, always retains a certain amount of the chlorides. These exudations may either have been deposited at the time when the blood yet possessed an excess of chlorine, or they may have appeared after the chlorine had ceased to be discharged in the urine in appreciable quantities. However, that may ultimately be decided by analysis; what I desire to point out is, that the absence of the chlorides in the urine does not necessarily involve the absence of chlorine from exudations. For the latter are produces of diseased action derived directly from stagnant blood, and certainly not subject to the specific laws of secre

tion. The presence of chlorine in sputa, therefore, at a time when it is absent from the urine, is not sufficient proof of a determination of the chloride towards the inflamed lung; a proposition which, moreover, loses all probability from the partial or total disappearance from the urine of the chloride in all acute diseases. We may mention bronchitis, typhus, acute rheumatism, pyæmia, pleuritis, as diseases in which this diminution of the chlorides has been prominently observed. We have seen the influence which different quanti ties of chlorine taken with the food exert upon the amount of chlorine discharged by the urine during health. It in therefore easy to believe that the diet of patients has the greatest influence upon the amount of chlorine in pathological urine; and that the chlorine is diminished or absent because these patients take little or no food, and what they take generally contains no salt. One important point, however, must not be lost sight of; namely, that urine containing no appreciable trace of chlorine is secreted from blood containing a certain amount of it; from which it follows that the composition of the blood is such as not to allow any further removal of chlorine, or that the kidneys have lost their secretory activity as regards chlorine, as well as (which has been seen to be the case) with reference to water.

The analysis of the amount of chlorine in the urine of patients may, therefore, afford an insight into the degree of the pathological action taking place in the body. A continuous decrease of chlorine in the urine is an indication of the growing severity of the disease, the intensity of which will be greatest when the chlorine in the urine falls to a minimum, say 05 grammes, or disappears altogether. This may be the combined effect of an entire loss of appetite, copious serous diarrhoea, or other serous exudations, of secretions such as perspirations, and of the want of secreting power of the kidneys. A rise in the amount of chlorine, on the other hand, indicates a steady abatement of the acuteness of the disease, and is a good measure of the returning appetite and improved digestive powers of the patient.

In chronic diseases the excretion of chlorine is, according to Vogel, generally diminished, correspondingly with the low state of nutrition and moderate appetite of the patients of that class. To this rule, however, diabetes insipidus makes an exception-a disease, during the entire or partial course of which a considerable excess of chlorine is discharged, parallel to the increased amount of other solids. In a case of that description Vogel found the amount of chlorine dis

charged by the urine so much increased for a period, that on one day it was 290 grammes in weight. The same observer found that dropsical patients, when under the influence of diuretics, discharged an increased amount of chlorine, which evidently had passed into the tissues and cavities dissolved in the exudations and transudations. One of these patients discharged 330 grammes of chlorine (equal to 55·0 grammes of chloride of sodium), 280 grammes, and 21 grammes of chlorine, on three successive days without having taken any more salt than usual with his food. In these and other chronic cases the amount of chlorine in the urine is a measure of the digestive powers of the patient. A quantity of chlorine, amounting to from 6 to 10 grammes for twentyfour hours, may lead us to infer a good digestion; a quantity of chlorine, however, below 5 grammes for the same time, shows impaired nutrition, provided that the decrease have not been preceded by a diet containing little or no chlorine, or by any of the causes which have been above enumerated as diminishing the amount of chlorine in the blood, such as serous diarrhoea, exudations, and perspirations. An increase in the amount of chlorine, when not caused by an excessive ingestion with the food, is indicative of diabetes insipidus. In dropsical and hydræmic conditions, an increase of the amount of chlorine is a favorable symptom. (Vide Vogel, p. 260.)