URINE. 191 



Milky urine is always turbid, of a yellowish-white colour, 

 sometimes like milk, and when examined under the microscope, 

 exhibits a quantity of fat-vesicles. Upon the application of heat to 

 urine of this nature, coagulation will take place if a considerable 

 amount of lactic acid is present, and then only a moderate tem- 

 perature (86 to 104 F.) is sufficient. If it does not coagulate 

 at this temperature, neither will it do so at the boiling point, 

 as I have proved in an experimental mixture of milk with urine. 

 If, however, albumen should also be present, the urine will 

 coagulate on being boiled. On the addition of a few drops of 

 acetic, or dilute sulphuric or hydrochloric acid to a little of this 

 urine, flocculi of coagulated casein will be formed if a moderate 

 heat is applied. In order to determine the quantity of casein 

 we must add a little acetic acid to a weighed portion of mode- 

 rately warmed urine, and allow it to digest till the white flocculi 

 of acetate of casein have separated themselves, and the urinary 

 fluid has become clear. 



The flocculi must be collected, washed, dried, and weighed. 

 This is most readily effected on a light filter of known weight, 

 which must be deducted, in order to give the true weight of 

 the casein. The fat becomes entangled in the precipitated 

 acetate of casein, and the filtered fluid exhibits only a few scat- 

 tered fat-vesicles swimming in it. The fat may be separated, 

 and its amount determined, either from the dried residue of 

 the urine, or from the dried casein, by extraction with ether. 

 The casein must be determined from a separate portion of 

 urine ; after this constituent has been separated the urine may 

 be evaporated, and the urea and water-extract determined from 

 the residue. 



6. Brown pigment of the bile. (Biliphcein.) 



It is no uncommon occurrence to find the urine tinged with 

 this substance ; in icterus it is always present. Urine of this 

 sort is of a saffron, dark yellow, or yellowish-brown colour, 

 and its sediment, if it contains one, is usually of a yellow 

 or brown colour also. We cannot, however, always decide 

 upon the presence of biliphasin from the colour of the urine, 

 since hsemaphsein (the peculiar colouring matter of the urine) 

 is capable of producing a similar tint. It is a peculiarity 



