" I believe that there is now required only a small number of good and correct observa tions to establish a fixed rule for the remedies necessary in various cases. Future properly directed experiments will prove whether san guification is absolutely dependent upon the presence of alkaline phosphates or not ; we shall be able to determine whether weak so lutions of alkaline phosphates are not the best solvents for uric acid deposited in the bladder ; and likewise what is the influence which aliments rich in sulphur, such as mus tard, for instance, exercise upon the se paration of uric acid in the bladder, in con sequence of the formation of sulphuric acid. At any rate, we may, by a judi ciously-selected diet, alter with positive cer tainty, and at pleasure, the nature of the urine ; we may, without causing any injury to health, keep it alkaline for a long time, by adopting a vegetable diet ; and this is cer tainly the first condition necessary to insure the entire prevention of the formation of uric acid, as is the case with the herbivorous animals. By its combination with an alkaline base, uric acid must in the organism resolve itself into its ultimate oxygen compounds with the same facility as other organic acids, if the physician prohibits all substances to be taken as food which, like wine or fat, take possession of the oxygen necessary for the transformation of uric acid into carbonic acid and urea.
" The carbonated alkali in the urine of herbivorous animals is separated from the blood by the kidneys ; the urine derives it from the blood ; it is certain, therefore, if we examine the blood one hour or a few hours after the animal has partaken of food, we must find in it this alkali in the same state as it is found in the urine, and that at other periods of the day the ashes of the blood may not contain the least trace of free alkali. But the free alkali does not co-operate in the vital process in the animal organism ; or, if it is necessary in this process, the part which it has to perform may be undertaken with the very same effect by the bibasic and tribasic alkaline phosphates.
" In like manner, when we are contemplat ing the presence of hydrochloric acid in the gastric juice, we must remember that the alka line bases, soda, potass, lime, magnesia, are present in the aliments whilst in their natural state, invariably in the form of salts ; that is, in combination with phosphoric acid, or with organic acids. When, therefore, in the diges tive process, hydrochloric acid is supplied by the gastric juice, the first action of this acid is confined to the decomposition of these salts ; the hydrochloric acid withdraws lime from the phosphate of lime ; potass, or soda, chloride of calcium, or chloride of sodium or potassium, is formed on the one hand, and acid phosphate of soda or potass, or acid phosphate of lime, on the other ; or acetic acid, paratartaric acid, or citric acid, are liber ated by the decomposition of the salts of these vegetable acids contained in the ali ments. At a certain stage of digestion the
chyme will, according to the nature of the food partaken of, contain acid phosphates or free vegetable acids ; and it is only upon the supply of gastric juice continuing, that thus, upon the amount of the hydrochloric acid increasing, we may detect, by analysis, free hydrochloric acid in the chyme : the gas tric juice taken from an empty stomach con tains invariably free hydrochloric acid, or acid phosphates." Lehmann has made some very interesting observations, published in the " Journal flir Praktische Chemie," by which he has shown the effects of diet on his own urine. He first observed the results produced by his ordinary diet during thirteen days, and found that the urea amounted on an average to about 46 per cent. of the whole of the solid matter excreted. The average quantity of urea excreted during the 24 hours amounted to about 500 grains.
During six days, on an ordinary diet, the uric acid excreted averaged about 1.089 parts per 1000, and the amount excreted during the 24 hours was about 18 grains.
On a purely animal diet, Lehmann found the amount of solid matters discharged in the urine during the 24 hours was much increased. The urine became pale in colour and strongly acid. On the addition of nitric acid, crystals of nitrate of urea were immediately formed, and uric acid was deposited in large crystals.
By careful analysis, however, Lehmann de termined, that though a purely animal diet increases the proportion of urea excreted during the 24 hours, the amount of uric acid is not by any means materially influenced.
The earthy phosphates were discharged in large quantities under a purely animal diet, rising to about three and a quarter times as much as when ordinary mixed diet was taken.
With respect to the effects of a vegetable diet, Lehmann observed the urine to become of a darker colour than natural, and to remain of an acid reaction much longer than ordinary human urine. The following tables of com parison have been constructed by Franz Si mon from the results of Lehmann : they possess a high physiological value.
From the above it would appear, that the amount of urea is always diminished by a vegetable diet, while the proportion of uric acid excreted is not materially affected. Leh mann ascertained also, by other experiments, that the amount of lactic acid, phosphates, and lactates was scarcely changed, whether the subject of experiment lived on an animal, or vegetable, or a mixed diet. A vegetable diet was found to increase considerably the daily discharge of extractive matters ; while far less was passed under an animal diet than when either a mixed or vegetable diet:was used.