* I ;? ^ IR 



The urine cannot be voided at the same time as the faeces, when these? 

 by their hardness, compress the prostatic and the membranous part of the 

 urethra, situated before the lower extremity of the rectum. It is diffi- 

 cult, and often impossible, to void urine during; a violent erection, as the 

 parietes of the canal are then closely applied to each other, by the tur- 

 gescence of the corpus spungiosum and of the corpora cavernosa of the 

 penis. The mode of sensibility of the urethra, is besides changed in 

 such a manner, that it is calculated to permit only the emission of the 

 seminal fluid. 



When the bladder is completely emptied, it sinks behind the pubis ; 

 the tumour which it formed above these bones, while in a state of dis- 

 tension, collapses, the abdomen becomes less prominent, respiration more 

 free, and there is a general feeling of lightness. The bladder cannot be 

 completely evacuated, unless the pelvis is gently inclined forward ; its 

 has fond) which is on a lower level than its neck, would, in any other 

 posture, retain a certain quantity of urine. 



XXXVI. Of the physical jiro/ierties of Urine. As this fluid varies in 

 quantity in a healthy man, according to the quantity and diuretic quali- 

 ties of the drink, the state of sleep or waking, the condition of the se- 

 cretions, arid especially of the perspiration, it is very difficult to deter- 

 mine, accurately, its proportions. Nothing varies more than its quantity, 

 as may be ascertained, by comparing the different calculations on that 

 subject, of a great number of physiologists. At times, the urine is less 

 in quantity than the drink that has been taken in, at others, more. It 

 may be affirmed, however, that the quantity of urine voided in twenty- 

 four hours, is equal to that of the insensible perspiration in the same time, 

 and it may, therefore, be estimated at between three and four pounds, in 

 a healthy adult. Its colour varies, from a light lemon yellow, to an or- 

 ange, approaching to red. Its smell and flavour are peculiar, and dis- 

 tinguish it from every other animal fluid. Its colour is, in general, dark- 

 er, its smell and flavour stronger and more pungent, as it is less in quan- 

 tity, as the circulatory system is more active and powerful, and as the 

 substances of our food are more animalized. We all know how fetid and 

 how scanty is the urine of carnivorous animals; how offensive to the 

 smell is that of the cat ! The specific gravity of urine is greater than 

 that of distilled water, and varies, according to the quantity of saline 

 and other substances, which it holds in solution : it is, likewise, slightly 

 viscid, but not ropy like the serum of the blood, the bile, the saliva, and 

 other albuminous fluids. 



XXXVII. Of the chemical properties of Urine*. The peculiar qualities 

 of urine are always more marked in a powerful and adult male, than in 

 children, women, and weakly persons. By chemical analysis, the urine 

 is found to contain eleven substances, dissolved in a considerable quan- 

 tity of water, viz. urea, a gelatinous animal master, muriates and phos- 

 phates of soda and ammonia, in separate or in triple salts, phosphate of 

 lime, phosphate of magnesia, phosphorus, uric and benzoic acids. Be- 

 sides these substances which are constantly found in human urine, this 

 fluid may contain a great number of others; and if it be true that the 



of the pelvis : under such circumstances in women, it is impossible to introduce the 

 catheter, except by increasing the curve of the instrument. faithor's Note. 



* For some observations on the physical and chemical properties of urine, see AP- 

 PENDIX, Note P. 



