THE SECRETIONS. 



tion of a phosphate. For this purpose, 10.085 grammes of well 

 crystallized sodium phosphate (Ka 4 HP0 4 -f 12H,O) are dis- 

 solved in distilled water, and the solution diluted to one litre. 

 Fifty cubic centimetres contain 0.1 gramme of P 2 5 . 



Then 100 grammes of sodium acetate are dissolved in 900 c.c., 

 of distilled water, and 100 c.c., of acetic acid added. 



The solution of uranium acetate is made ty dissolving com- 

 mercial uranic oxide in acetic acid, diluting and filtering; or, 

 instead, a solution of uranium nitrate may be made by dissolv- 

 ing the crystallized salt in water, and diluting. The solutions 

 are intended to contain 20.3 grammes of uranic oxide in one 

 litre of solution. 



Having obtained the solution of uranium acetate or nitrate, 

 its strength is determined in the following manner: 50 c.c. of 

 the standard solution of sodium phosphate are placed in a 

 beaker, and f> e. c., of the acid solution of sodium acetate added. 

 The uranium solution is poured from an accurately graduated 

 burette, until precipitation ceases. Then a few drops, of a 

 solution of potassium ferrocynnide are placed on a porcelain 

 slab, and after each addition of uranium solution to the phos- 

 phate, a drop of the mixture is taken up by means of a glass 

 rod and brought in contact with the ferrocyanide. As soon as 

 an excess of uranium solution has been added, the character- 

 istic reddish-ln-own color of uranium ferrocyanide is observed. 



It is convenient to graduate the solution of uranium so that 

 I'll cubic centimetres shall bo exactly equal to 50 c.c. of the 

 standard solution of phosphate of soda, z.e., to 0.1 gramme of 



nalyzing urine by means of solutions of uranium, it is 

 convenient to operate on 50 c.c. This quantity of urine is 

 treated with the acetate of sodium solution and heated on the 

 water-bath to a temperature approaching 100 C. ; it is then 

 treated with the solution of uranium as previously described. 

 198. Determination of the Quantity of Sulphuric 

 Acid in Urine. The quantity of sulphuric acid in urine is 

 letermined by precipitating with chloride of barium and 

 weighing the dried and burned precipitate of barium sulphate ; 

 from this the amount of sulphuric acid can be calculated. It 

 i> usual to state the amount of sulphuric anhydride (SO 3 ) cor- 

 responding to the sulphuric acid existing in the urine. ' 



For details as to the precaution to be used in determining 

 the amount of sulphuric acid by precipitation, the student is 

 >ferred to Presenius'a Quantitative Analysis. The manipula- 

 tions involved in such an analysis, however simple it may be, 

 can only be learned in a laboratory devoted to pure chemistry, 

 t has been suggested that the sulphuric acid in urine should 

 letermined by means of a standard solution of chloride of 

 barium ; the metnod is one, however, which is tedious, and ' 



