THE URINE. 185 



settle and then adding a few drops more of the silver nitrate 

 solution to the clear fluid, when no further precipitate of sil- 

 ver chloride will be formed. Heat to boiling with constant 

 stirring, and continue the boiling for several minutes. Decant 

 the clear liquid through a Gooch crucible, and wash the pre- 

 cipitate by decantation with 200 cc. of hot water contain- 

 ing 8 cc. of nitric acid (sp. gr. 1.2) and 2 cc. of a 1 per cent, 

 silver nitrate solution. During the washing by decantation 

 add the wash-water in small portions and break up the pre- 

 cipitate with a glass rod. Finally transfer the precipitate 

 completely to the Gooch crucible, wash with 200 cc. of cold 

 water and then with 25 to 30 cc. of 95 per cent, alcohol. 

 Dry at 145-150 and weigh. Continue the heating at this 

 temperature until the weight remains constant. From 

 the weight of the silver chloride obtained calculate the 

 equivalent in hydrochloric acid, as shown in the following 

 example : 



Twenty-five cubic centimeters of the dilute hydrochloric 

 acid gave as the mean of two duplicate analyses 0.7751 g. AgCl. 

 Molecular weight of AgCl = 143.38. AgCl : HC1 : r 0.7751 : x. 

 Molecular weight of HC1 = 36.46. 143.38 : 36.46 : : 0.7751 : x; 



s = 0.1971g. HClin25cc. 

 ^ = 0.007884 g. HC1 in 1 cc., or 7.884 g. HC1 per liter. This 



may be converted into N/5 hydrochloric acid containing 

 7.292 g. (-J- of 36.46) of HC1 per liter, as follows: 



7.292 :1000: : 7.884 :x; 

 3 = 1081.1 cc. 



x - 1000 cc. = 81.1 cc., the amount of distilled water to be 

 added to exactly one liter of the dilute hydrochloric acid 

 (containing 7.884 g. HC1 per liter) to make it fifth-normal 

 hydrochloric acid (containing 7.292 g. HC1 per liter). 



