514 OF SECRETION AND EXCRETION. 



grains. In regard to the effects of exercise ou the excretion of acids by the 

 urine, Klupfel 1 found that it was augmented to the extent of 44.8 per cent, 

 by exercise, whilst Sawicki 2 obtained only variable and chiefly negative re- 

 sults. When sulphuric acid or soluble sulphates are taken into the system 

 per se, they partly find their way out of it by the kidneys ; the proportion of 

 sulphuric acid in the urine being for a time augmented, although the increase 

 is not considerable until some hours have elapsed after the introduction of 

 these substances into the stomach. 3 They are not increased on a non-nitro- 

 genous diet by exercise (Parkes). The absolute amount of sulphuric acid 

 varies from 35 to 50 grains per diem. The amount of Alkaline. Phosphates 

 in the urine is usually about half that of the alkaline sulphates. The acid 

 of these also is ordinarily generated within the system, by the oxidation of 

 the phosphorus originally introduced in the protein-compounds ; and thus, 

 as in the case of the sulphates, the quantity of them which is excreted by the 

 urine bears a certain relation to the amount of these compounds ingested as 

 food, and also to the amount of muscular tissue which has undergone disin- 

 tegration by exercise. But it further appears that there is a special relation 

 between the quantity of the alkaline phosphates in the urine, and the amount 

 of disintegration of the nervous tissue ; as might have been suspected from the 

 fact, that this tissue is distinguished by the very large proportion of phospho- 

 rus, united with fatty acids, which it contains. And a marked increase of 

 these salts is observed in those inflammatory diseases of the brain, in which 

 there is reason to believe that an unusually rapid disintegration of its texture 

 is taking place. 4 The Earthy Phosphates usually bear but a small proportion 

 to the Alkaline ; but their presence in the urine comes to be of great impor- 

 tance with reference to the precipitates which they form in particular condi- 

 tions of that secretion. From the researches of Dr. Bence Jones (loc. cit.) it 

 appears, that the quantity of these phosphates in the urine chiefly varies with 

 the amount of them contained in the food, into many articles of which they 

 enter largely, 5 but he has also ascertained that their formation within the 

 system is determined by the presence of their bases ; for if any earthy salt, a 

 little chloride of calcium or sulphate of magnesia for instance, be taken into 

 the system, the quantity of earthy phosphates in the urine undergoes an in- 

 crease. The small quantity of carbonate of lime taken into the system with 

 the food, or set free by the slow disintegration of the osseous tissue, is proba- 

 bly excreted in Man almost entirely in the form of phosphate; although of the 

 much larger amount ingested by herbivorous animals, a considerable propor- 

 tion is excreted in the urine in its original state. The Earthy Phosphates, 

 although insoluble in water, are soluble in all acid liquids ; and they are held 

 in solution in Urine, like the urates, by the acid phosphate of soda. Their 

 precipitation in an alkaline state of the urine is owing to the want of this 



1 Hoppe-Seyler's Chem. Unters., 1868, Heft 3. 

 ' Prhiger's Archiv, Bd. v, p. 28-5. 



3 Dr. Bence Jones in Philosophical Transaction?, 1849. 



4 See Dr. Bence Jones's valuable series of Papers in the Philosophical Transactions 

 for 1845, 1847, and 1850, and in the Medico-Chirurgical Transactions for 1847 and 

 1850; also Byasson, Op. cit., p. 612. It is curious to observe, that whilst the in- 

 crease in the alkaline phosphates in Inflammatory affections of the nervous centres 

 is very marked, there appears to be a positive diminution of them in Delirium Tro- 

 mens. A certain allowance must be made, however, for the abstinence from food, 

 which will of itself occasion a reduction in the quantity excreted. 



5 The experiments of Neubaur (Journal f. pract. ('hem., 1860, p. 96), Riesel (Hoppe- 

 Seyler, Mcd. Chem. Untersuch., Heft 3, 1809), and Soborow (Ccntralblatt, f. d. 

 Med. "Wiss., 1S~^, p. G09) all show that when taken in excess the salts of lime are 

 very rapidly and completely eliminated by the urine, the whole being discharged in 

 the course of a lew hours. 



