URINE. 



the acids only of the urine, having treated at length of urea 

 in its proper place. 



The acids of the urine may be conlidered as of two kinds, 

 thofe peculiar to it, and gener .ted in the aA of fecretion ; 

 and thofe common to it and the blood, and which of courfe 

 pre-exilled in that fluid. In the firft clafs are comprifed the 

 fulphuric acid, the uric acid, and occafionally the benzoic 

 and carbonic acids ; in the fecond, the phofphoric and lattic 

 acids, which appear to be more abundant in the urine than 

 the blood, and confequently may be fuppofed to be formed in 

 part in the kidneys alfo ; in the third, the muriatic and fluoric 

 acids which appear to pafs from the blood to the urine without 

 any increafe from the kidney. As by the laws of chemical 

 affinity thefe acids will unite with any alkaUne bafe that may 

 be prefent, and faturate themfelves with it in the order of the 

 force of their refpedtive affinities, it mud follow, as juftly 

 obferved by Berzelius, that when the quantity of alkali is 

 infufficicnt to faturate all the acids prefent, the weakeft acids 

 muft be thofe that will remain uncombined, and will confe- 

 quently impart to the urine their peculiarly acid charafters. 

 Tiiefe therefore muft necefTarily be the laftic and the uric 

 acids. 



The fuljfhuric acid does not exift in the blood, but it is 

 found in confiderable quantity in the urine. Rouelle fenior 

 long ago pointed out this faft, but it feems to have been re- 

 garded by fubfequcnt chemifts rather as an accidental than as 

 a conftant occurrence. Berzelius, however, has flievvn the 

 contrary, and Hates that he has good reafon for believing that 

 this acid is an eflential conftituent of the urine. The fame 

 excellent chemift alfo has fliewn that the whole of the fulphur 

 contained in the blood is not acidified in the kidneys, but 

 that a portion of it ftill remains in an unaltered though com- 

 bined ifate in the urine. 



The leading properties of the uric acid have been difcuflfed 

 under its proper head ; we fliall therefore confine ourfelves 

 here to a few circumftances connefted with its formation and 

 reparation from the urine. The red cryftalline depofit, or gra- 

 ▼tl, which occurs in urine that has been kept for a few days, 

 confifts chiefly of uric acid united with the colouring matter 

 of the urine, or, according to Berzelius, with ammonia. What 

 is termed alfo the pink, or lateritious fediment , a fubftance fre- 

 quently formed ui derangements of the digeftive organs, and 

 efpecially in gout, and which was formerly confidered a dif- 

 tinft principle by Prouft, who named it the rofacic acid, has 

 been lately fhewn to confift chiefly of uric acid, combined 

 with colouring matter and foda. 



The benzoic acid, according to Scheele, is fometimes found 

 in the urine of infants. Berzelius, however, has never been 

 able to deteft it, and feems to doubt if it ever exifts in healdiy 

 human urine. 



With refpeft to the carlotuc acid, Berzelius feems to doubt 

 if it ever exifts in healthy unne, and fuppofes its occafional 

 prefence to arife from the decompofition of urea. Dr. Mar- 

 cet ftates that he has fometimes found traces of carbonic 

 acid in the urine, and fometimes not ; and concludes, " that 

 the evolution of this gas from the urine, whether arifing 

 from the prefence of uncombined carbonic acid, or from 

 fome decompofition of the animal matter contained in that 

 fluid, depends upon certain ftates of the body at the moment 

 the urine is fecreted, rather than upon the introduftion of the 

 gafeous acid through the digeftive organs." 



The phofphoric acid, for the reafons before mentioned, can 

 hardly be ever fuppofed to exift in urine in the free ftate. 

 Its faJts, however, form very important ingredients of that 

 fluid. What is ieirasA tvhite gravel, or /and, ufually con- 

 fifts of the phofphate of magnefia and ammonia, and of the 



I 



phofphate of li.me, and are perhaps chiefly formed in thtf 

 kidney. 



To the laliic acid, and the peculiar animal matters which 

 accompany it, Berzelius afcribes chiefly the acid properties, 

 as well as the peculiar colour and fmell of the urine. 



The mnriatic acid, and its compounds, the muriates of 

 foda and ammonia, exift in the urine, (more efpecially the 

 muriate of foda, ) in confiderable quantity. The muriate of 

 foda is probably never a product of fecretion, but derived 

 from the blood. The origin of the muriate of ammonia is 

 more obfcure. 



The prefence of a fmall portion of xhejluoric acid m urine 

 in combination with lime has been demonftrated by Berze- 

 lius ; but the exiftenceof this principle, as well as oi fdex in 

 the urine, refts at prefent, we believe, upon his authority 

 alone. 



The urine is not only liable to be much modified by difeafe, 

 but from the fame caufe occafionally contains fubftances 

 which never exift in it in a healthy ftate. The principal of 

 thefe are albumen, faccharine matter, and oxahc acid, all 

 which, as well as others, probably depend either upon a 

 fufpenfion or perverfion of the fecreting powers of the 

 kidney. 



Thus the albumen feems to be derived at once from the 

 blood. The faccharine matter, as ftated under Urea, ap- 

 pears to be formed by fome unknown procefs from that fub. 

 ftance, while the oxalic acid is probably derived from the 

 fame fource. 



The above obfervations apply to the human urine ; we 

 come now to make a few remarks upon the urine of other 

 animals ; a moft extenfive field of refearch, but which has 

 not at prefent been much inveftigated. 



Urine of the Lion and Tiger The urines of thefe ani- 

 mals, according to Vauquelin, clofely refemble one another, 

 and hkewife bear fome analogy to the human urine ; they 

 differ from it, however, in the following effential points : 

 they contain no uric acid, nor any combination of that prin- 

 ciple, as might have been expefted from the food on which 

 thefe animals live. They contain, however, a great propor- 

 tion of urea, though very httle muriate of foda. They 

 have a peculiar fetid fmell, which is derived, in part, pro- 

 bably from the ammonia developed from the decompofition 

 of the urea. This fmell is well known to be common to the 

 urine of all the fehne animals, and may in every inftance be 

 fuppofed to be owing to a fimilar caufe. 



The urines of the horf- and cow do not differ much from 

 one another, according to the fame chemift. Both become 

 muddy in coohng ; both are alkaline, and contain a large 

 proportion of carbonate of lime, benzoic acid, and urea, but 

 no uric acid. One thoufand parts of the urine of the horfe, 

 according to Fourcroy andVauquehn, are compofed of 



Water and mucus . . - 



Urea ------ 



Carbonate of lime - . . 



Benzoate of foda - - - - 



Carbonate of foda - . - 



Muriate of potafti ... 



The urine of the camel has been examined by Rouelle. 

 Its odour refembles that of the cow. Its colour is that of 

 beer ; it is not mucilaginous, and does not depofit carbonate 

 of lime. It is alkaline, and contains the carbonate, fulphate, 

 and muriate of potafti, and urea. Mr. Brande, who has 



fince 



