URINE 547 



The weight of S(V in the volume of urine taken may be determined by means of 

 the following proportion. 



Mol. Wt. Wt. of Mol. wt. 



BaSO 4 : BaSO 4 : : SO 3 : x(wt. of SO 3 in grams). 



Representing the weight of the BaSO 4 precipitate by y and substituting the proper 

 molecular weights, we have the following proportion : 



233.43 ' 7 80.06 : x (wt. of SO 3 in grams in the quantity of urine used). 



Calculate the quantity of SO 3 in the twenty-four-hour specimen of urine. 

 To express the result in percentage of SO 3 simply divide the value of x, as just 

 determined, by the quantity of urine used. 



Interpretation. The total sulphate excretion (ethereal and inorganic 

 sulphates) by a normal adult on a mixed diet is usually between 1.5 and 

 3.0 gram of SO 3 with an average of about 2.0 gram. The sulphuric 

 acid is derived but to a slight extent ordinarily from ingested sul- 

 phates, being mainly dependent on the sulphur of the protein ingested 

 and will consequently vary widely with the protein content of the diet. 

 From 75 to 95 per cent of the total sulphur of the urine is ordinarily 

 found as sulphate, the proportion being greatest on a high protein diet. 

 The sulphate excretion is increased in all conditions associated with 

 increased decomposition of body protein as in acute fevers and de- 

 creased whenever there is a decrease in metabolic activity. 



2. Inorganic Sulphates. Folin's Method. Place 25 c.c. of urine and 100 

 c.c. of water in a 200-250 c.c. Erlenmeyer flask and acidify the diluted urine 

 with 10 c.c. of dilute hydrochloric acid (i volume of concentrated HC1 to 4 vol- 

 umes of water). In case the urine is dilute 50 c.c. may be used instead of 25 c.c. 

 and the volume of water reduced proportionately. Add 10 c.c. of 5 per cent bar- 

 ium chloride slowly, drop by drop, to the cold solution and from this point proceed 

 as indicated hi the method for the determination of Total Sulphates, page 546. 



Calculate the quantity of inorganic sulphates, expressed as SO 3 , in the twenty- 

 four-hour urine specimen. 



Calculation. Calculate according to the directions given under Total Sul- 

 phates, above. 



Interpretation. On an average about 90 per cent of the total sul- 

 phates of the urine exists as inorganic sulphates but the proportion 

 of the sulphates existing in this form varies widely, being greater on 

 a high protein diet than on a very low protein diet. The amount 

 varies with the total sulphates (which see). 



3. Ethereal Sulphates. Folin's Method. Principle. The inorganic sul- 

 phates are removed with barium chloride and the conjugated sulphates then 

 determined after hydrolysis. 



Procedure. Place 125 c.c. of urine in an Erlenmeyer flask of suitable size, 



1 It is considered preferable by many investigators to express all sulphur values' in terms 

 of S rather than SO 3 . 



