XVII.] 



THE INORGANIC CONSTITUENTS OF URINE. 



lis 



(b.) All air-bubbles must be removed from the burette as well as 

 from the outflow tube. The latter must be quite filled with the 

 titrating solution. 



(c.) Fill the burette with the solution up to zero, and always 

 remove the funnel with which it is 

 filled. 



(d.) Read off the burette always in 

 the same manner, and always allow a 

 short time to elapse before doing so, 

 in order to allow the fluid to run down 

 the sides of the tube. 



(e.) The titrating fluid and the fluid 

 being titrated must always be thoroughly 

 well mixed. 



(/.) It is well to make two estima- 

 tions, the first approximate, the second exact. 



Fig 



Feathery Forms of Triple 

 Phosphate. 



11. Volumetric Process for Phosphoric Acid, with Ferrocy- 

 anide of Potassium as Indicator. — i cc of the SS. (Uranium 

 acetate) = .005 gram of phosphoric acid. 



Solutions Eequired. — Sodium Acetate Solution. — Dissolve 100 grams of 

 sodium acetate in 100 cc. pure acetic acid, and dilute the mixture with dis- 

 tilled water to 1000 cc. 



Potassium Ferrocyanide Solution.— Dissolve i part of the salt in 20 parts 

 of water. 



Uranium Nitrate Solution (i cc. =.005 gram H3PO4).— Dissolve 35 grama 

 of uranium nitrate in strong acetic acid, and dilute the solution to i litre. 



Apparatus Required. — Mohr's burette, 

 fitted in a stand, and provided with a 

 Mohr's clip ; piece ot white porcelain ; 

 tripod stand and wire-gauze; small beaker; 

 two pipettes, one to deliver 50 cc, the 

 other 5 cc. ; glass rod. 



(a.) Collect and carefully measure ^ 

 the urine passed during twenty-four 

 hours. 



(h.) Place 50 cc. of the mixed 

 and filtered urine in a beaker. Do 

 this with a pipette. Place the beaker 

 under a burette. 



(c.) To the urine add 5 cc. of the 

 solution of sodium acetate ; mix 

 thoroughly. 



(d.) Fill a Mohr's burette with 

 the SS. of uranium acetate up to zero, or to any mark on tiie 

 burette. See that the Mohr's clip is tihgt, and that the out- 



FlO. 58.— Burette ^[eniscns. 



