1169 



URINE. 



URINE. 



1170 



water, as to convert the urea into carbonate of ammonia. This is the 

 reason why urine speedily becomes alkaline, though acid when voided. 

 If the urine is filtered from the mucus as soon as passed, it remains 

 for a long time unchanged. 



The ultimate source of urea in the urine is undoubtedly the 

 metamorphosis of the muscular and nervous tissues of the body. It 

 has been found, that in proportion to the muscular exercise taken, is 

 the urea increased in the urine. Urea is also found in greater quan- 

 tities in the urine of children, in whom the vital processes are more 

 active than in the urine of adults. A question has arisen, as to 

 whether urea is formed by the secreting energies of the kidney, or is 

 merely separated from the blood by this organ. The fact of urea 

 having been detected in the blood by Strahl, Lehmann, and others, 

 would lead us to the conclusion that the latter is the fact. Another 

 question then occurs, as to whether the urea in the blood is the 

 result of the immediate metamorphosis of the tissues, or is formed by 

 the intervention of other compounds. It appears that urine is easily 

 formed from creatin, a substance that is the result of the decompo- 

 sitiou of flesh, and it is not improbable that creatin is the source of 

 urea in the blood. Although it has been generally supposed from the 

 effect of arresting the function of the kidney that urea in the blood is 

 a deadly poison, recent experiments have shown that a considerable 

 quantity of urea may be injected into the blood without the destruction 

 of life. It is probable that urea destroys life by becoming converted 

 in the blood into carbonate of ammonia. 



The quantity of urea secreted depends, as stated above, on age and 

 muscular exertion, but these are not the only conditions which affect 

 the quantity of urea in the urine. The quality of the food has an 

 especial influence on this substance. Bischoff found, in a course of 

 experiments on dogs, that one dog when taking 4000 grammes of beef 

 discharged 190 grammes of urea daily, and when living on 500 

 gramme* of potatoes and 250 grammes of fat excreted not more than 

 from 6 to 8 grammes. Siegmund also, in a series of experiments 

 performed on rabbits, found that the quantity of urea gradually 

 dminishes with the quantity of the food. 



Uric Acid invariably exists in healthy urine, and can be easily 

 precipitated by the addition of any acid. As the production of this 

 acid in the system is intimately connected with the nature of the 

 food and the powers of digestion, deposits of this acid, as might be 

 expected, are of frequent occurrence. This acid is either deposited in 

 the form of powder (or, as it is usually called, amorphous sediment), 

 or in the form of crystals and large concretions. The amorphous 

 sediment varies extremely in its colour, from snow-white to fawn 

 colour or reddish-brown, occasionally assuming a series of beautiful 

 tints, varying from the most delicate pink to the brightest carmine, 

 or very nearly to the deepest crimson. These varieties of colour 

 depend on the greater or less proportion of the colouring-matter of 

 urine, and a peculiar principle (phosphate of ammonia) developed in 

 the kidneys. In this form the uric acid is usually in combination 

 with ammonia. Healthy urine contains urate of ammonia to the 

 amount of about 1-8 00th part, and the salt requires about 480 times 

 its weight of cold water to dissolve it. We see therefore that if by 

 any derangement in the digestive organs the quantity of urate of 

 ammonia should be increased in the urine, a portion of it would of 

 necessity be thrown down, as the urine would not be sufficient to hold 

 the whole of it in solution. Urine containing this amorphous deposit 

 varies in colour according to its sediment It is always acid, and 

 usually of high specific gravity, and is rendered transparent by the 

 application of beat, unless the urine be albuminous cr contain mucus. 



When a deposit of urate of ammonia is examined under the 

 microscope, it is found to be made up of a series of amorphous 

 granules, presenting no approach to a crystalline arrangement, unless, 

 as very frequently occurs, free uric acid be present. On gently warm- 

 ing the drop of urine submitted to examination the deposit vanishes, 

 and then any crystals of uric acid. 



Uric Acid is ofteu deposited in a crystalline form, and is found most 

 generally of a jellow, orange-red, or brick-dust colour, never however 



Uric Acid Cry.taK 



.ting the beautiful carmine tints occasionally possessed by urate 

 of ammonia. It in sometimes met with isolated and unmixed with 

 any amorphous d-"po>it(i, but more generally is found in company with 

 the urate of ammonia. On being allowed to subside two distiuct 

 layers are formed, the lowest consisting of uric acid, ofteu in crystals 

 BAT. HWT. D1V. VOL. IV. 



sufficiently large to be distinguished by the unassisted eye ; and above 

 this a dense stratum of amorphous urate. Under the microscope uric 

 acid presents a number of forms, but the rhomboid of a tolerably 

 distinct lozenge-shape is the most frequent form. Several secondary 

 forms, probably depending on a variable portion of colouring-matter 

 being present, frequently occur ; among these are the table, the 

 flattened cylinder, sharply serrated lozenges, and stella formed by the 

 cohering of elongated rhombs. 



Uric Acid appears to be formed in the system under the same cir- 

 cumstances as urea; but its formation in the blood seems to be 

 anterior to the urea. Uric acid appears to be converted into urea by 

 the process of oxidation, hence its development is increased by 

 sedentary pursuits, and arrested by active exercise. The acidity of 

 urine does not depend so much on uric acid as on acid phosphate of 

 soda, which is formed by some acid uniting with the soda of the 

 phosphate and converting it into a superphosphate. The formula of 

 Uric Acid is C 10 ,N 4 ,H 4 ,O e . 



Although lactic acid is said to be present iu human urine, it does 

 not appear that it occurs in healthy human urine ; it is very soon 

 developed in the urine when the oxidation iu the blood is to any 

 extent impeded. Hence it is found when fever is present, and iu those 

 disturbances of the respiratory and digestive organs which lead to a 

 deficient oxidation of the blood. 



The extractive matters of the urine referred to iu the analyses con- 

 sist of substances of which our knowledge is daily increasing. Thus, 

 creatin and creatinin are found in normal urine, although their 

 quantity and relations have not been well made out. We may also 

 refer to this head hippuric acid. It is well known that when animals 

 take food containing benzoic acid, that their urine contains hippurio 

 acid. Particular kinds of diet favour the development of hippuric 

 acid at the expense of uric acid, whilst a mixed diet is unfavourable 

 to the development of hippuric acid. Formic acid may be also men- 

 tioned here as a substance recently detected in healthy urine, and 

 probably included in extractive matters. 



The colouring matters of the urine are not specially named iu 

 chemical analyses. That some one substance, accordingly as it abounds 

 or is absent, produces the various shades of yellow, red, and brown 

 observed in urine, is not improbable. Vogel, who has devoted much 

 attention to this subject, is of opinion that the urine-pigment is formed 

 from the hscmation of the blood, and is produced by a decomposition 

 of the blood-corpuscles. On this ground he regards the amount of 

 pigment in the urine as an index to the amount of disintegration of 

 the blood-cells in a given time. 



Mucus always exists in healthy urine in minute quantities, and the 

 following are the appearances which it assumes : After the urine has 

 stood for some time in a tall glass vessel, the lower strata of the fluid 

 will be found to have lost their transparency, and an exceedingly light 

 nebulous-looking substance will be found floating in the vessel. If 

 collected in a filter, mucus, when moist, is always more or less trans- 

 parent ; and when dried, it has a shining appearance. Mucus is not 

 coagulated by boiling, which distinguishes it from albumen ; it is in 

 great part soluble in the acetic and nitric acids, but not in the sul- 

 phuric acid ; it is also soluble in caustic potass. Under the microscope 

 it presents cells larger than those of the blood, and delicately granu- 

 lated on their surface. With these will be found, in the transparent 

 liquid, a number of minute granular points. 



Sulphuric Acid and Sulphates. These are formed by the oxidation 

 of the sulphur of the protein-compounds ; and it has been shown 

 by Dr. Btuce Jones, that they are abundant in proportion to the 

 destruction of the tissues and the oxidation of the sulphur. 



Phosphoric Acid and Phosphates. These appear to be derived as 

 the sulphates from the disintegration of the tissues containing phos- 

 phorus, which is more especially the case with the nervous. The 



Triple Phosphate Crystals. 



phosphates of the alkalies are found to be iucreased in diseases in 

 which the activity of the nervous system is increase 1. The phosphates 



4 v 



