URINE. 8& 



along physical lines has been in this direction, in the hope 

 that the results will be of value for diagnostic purposes. 



At present it is customary to determine the quantity 

 of a given base or acid radical and then to express it 

 empirically in terms of a compound of this radical, the 

 quantity of which is considered to predominate in the mix- 

 ture. Thus chlorine is expressed as NaCl, potassium as K 2 0, 

 etc. The ordinary inorganic acidic radicals (anions) of the 

 urine are Cl', SO/', PO/", and CO/' and the basic radicals; 

 (kations), NH/, 1C, Na', Ca", Mg", with traces of Fe". 



ACIDIC RADICALS. 



(a) Chlorides. These are present combined principally 

 with Na and K. Acidify some of the urine with HN0 3 and 

 add a drop of AgN0 3 . Prove that this precipitate is AgCl. 



(&) Sulphates. These occur in two forms, viz., preformed 

 or sulphate-sulphuric acid and ethereal or combined sulphuric 

 acid. The former precipitates directly from the urine by the 

 addition of BaCl 2 in an acid reaction, the latter only after the 

 previous boiling of the urine with a mineral acid. Acidify 

 some urine with acetic acid and add an excess of BaCl 2 . 

 Prove that this precipitate is BaS0 4 . Filter (filtrate must 

 be clear), and to this add a few c.c. of concentrated HC1 and 

 boil a few minutes. A turbidity is indicative of the presence 

 of ethereal sulphates. Explain this. 



Sulphur in the organic or lead-blackening form may also 

 be present in the urine as a constituent of taurine, cystine, 

 KSCN, etc. Place some urine in a flask with a few pieces of 

 pure zinc and add enough HC1 to cause a gentle evolution of 

 gas. Partially close the mouth with a piece of filter-paper 

 moistened with lead acetate. In the presence of organic sul- 

 phur the paper is blackened. Explain this. 



