URIC ACID, URATES, ETC. 99 



but a graduated burette is substituted for the graduated collect- 

 ing tube. 



(a. ) Use this apparatus in a similar manner. 



(6.) Read off the number of cc. of N evolved, and from 

 this calculate the amount of urea. Every 37 '3 cc. N = 0'l 

 gramme urea. 



9. Solutions required. 



A. FOR DUPRE'S APPARATUS. 



Hypobromite Solution. Dissolve 5 cc. of bromine in 45 cc. of 

 a 40 per cent, solution of caustic soda. 



N.B. This solution does not keep, and must be freshly pre- 

 pared. 



B. FOR STEELE'S APPARATUS. 



Hypobromite Solution. 20 grammes of caustic soda are dis- 

 solved in water, and the solution is diluted to 250 cc. ; after cooling, 

 add 5 cc. of bromine, and mix. Keep in a stoppered bottle in 

 the dark; as it soon decomposes, it should be made fresh. 



10. Use also Charteris's apparatus. The bromine and caustic 

 soda are mixed in a marked measure, so that the hypobromite is 

 always fresh, while the collecting tube for the N is so graduated 

 as to indicate a certain percentage of urea. 



11. Study Squibb's apparatus. In all these cases directions 

 are supplied with the apparatus. 



LESSON XVII. 



URIC ACID, URATES, HIPPURIG ACID, 

 GREATININ, <Stc. 



1. Uric Acid (0 5 H 4 N 4 3 ) is the constituent of urine in which 

 (next to urea) the most N of the body is excreted, whilst in 

 birds, reptiles, and insects it forms the chief nitrogenous excre- 

 tion. 



