386 PHYSIOLOGICAL CHEMISTRY. 



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 volumes 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 barium 

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

 point proceed as indicated in the method for the determination of 

 Total Sulphates, page 384. 



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 Sulphates, page 385. 



3. Ethereal Sulphates. Foliris Method. Place 125 c.c. of 

 urine in an Erlenmeyer flask of suitable size, dilute it with 75 c.c. of 

 water and acidify the mixture with 30 c.c. of dilute hydrochloric 

 acid (i volume of concentrated HC1 to 4 volumes of water). To 

 the cold solution add 20 c.c. of a 5 per cent solution of barium chlor- 

 ide, drop by drop. 1 Allow the mixture to stand about one hour, then 

 filter it through a dry filter paper. 2 Collect 125 c.c. of the filtrate 

 and boil it gently for at least one-half hour. Cool the solution, 

 filter off the precipitate of BaSO 4 , wash, dry and ignite it according 

 to the directions given on page 385. 



Calculation. The weight of the BaSO 4 precipitate should be 

 multiplied by 2 since only one-half (125 c.c.) of the total volume 

 (250 c.c.) of fluid was precipitated by the barium chloride. The 

 remaining calculation should be made according to directions given 

 under Total Sulphates, page 385. 



Calculate the quantity of ethereal sulphates, expressed as SO 3 , in 

 the twenty-four hour urine specimen. 



4. Total Sulphur. Osborne-Folin Method. Place 25 c.c. of 

 urine 3 in a 200-250 c.c. nickel crucible and add about 3 grams of 

 sodium peroxide. Evaporate the mixture to a syrup upon a steam 

 water-bath and heat it carefully over an alcohol flame until it solidi- 

 fies (15 minutes). Now remove the crucible from the flame and 



1 See note (2) at the bottom of page 384. 



3 This precipitate consists of the inorganic sulphates. If it is desired, this 

 BaSC>4 precipitate may be collected in a Gooch crucible or on an ordinary quanti- 

 tative filter paper and a determination of inorganic sulphates made, using the 

 same technique as that suggested on p. 385. In this way we are enabled to 

 determine the inorganic and ethereal sulphates in the same sample of urine. 



3 If the urine is very dilute 50 c.c. may be used. 



