APPARATUS. 331 



tion, afterwards add an excess of a solution of nitrate 

 of uranium (one to ten) ; placing the thumb over the 

 end of the tube; mix thoroughly and allow the tube to- 

 remain quiet for twenty-four hours, after which time 

 the volume of precipitate may be read off, ever 2cc 

 .016 grains of phosphoric acid. 



Analysis for Earthy Phosphates, using the Marais 

 Tubes. Fill the tube to the ounce mark with filtered 

 urine as above, add an excess of strong liquor ammonia ; 

 mix well and set aside for twenty-four hours, at the 

 end of this interval note the volume of precipitate ; 

 each 2cc will correspond to .06 grains of the earthy 

 phosphates. 



Analysis for Sulphuric acid Standard Solution. In 

 3,000 grains of distilled water, dissolve forty-five and 

 three-fourth grains of pure chloride of barium; 200- 

 grains of this standard solution are equivalent to one 

 grain of sulphuric acid. If the solution be prepared 

 with due care, it may be used without special testing* 

 as it cannot be very well tritated. 



Solution of Sulphate of Soda. One part of soda to 

 ten of water. 



Analysis of Urine for Sulphuric acid. With a 

 pipette measure two fluid drachms of urine into a 

 beaker, dilute this with twice as much distilled Avater,. 

 adding also two or three drops of hydrochloric acid ; 

 bring the beaker over the spirit-lamp until the contents 

 become hot, fill the burette with the standard solution ; 

 deliver from the burette into the beaker a few drops 

 which will cause an instant precipitate ot the sulphate- 



