THE JOURNAL OF PHARMACOLOGY. 197 



most readily carried out, as it requires no heat -whatever. This latter method, how- 

 ever, will often cause a precipitate to appear in a given sample when certain sub- 

 stances derived from certain kinds of food or certain ingested medicaments are present 

 in the urine. It sometimes happens that a sample of urine presents unusual and un- 

 looked for difficulties in the way of analysis, and thus necessitates a consultation of the 

 more extensive books on this subject ; such occasions, however, are rare. It must 

 also not be forgotten that the ingestion of many of the newer remedies, particularly 

 the coal-tar derivatives, cause substances to be eliminated with the urine, which are a 

 source of trouble when certain reagents are applied, and give results quite at variance 

 with the usual. It, therefore, is well to ascertain, wherever possible, whether such 

 substances or any others capable of causing trouble have been administered prior to 

 the elimination of the sample under observation. 



PART FIRST. 

 Composition of Urine. 



Normal urine is an aqueous solution of various organic and inorganic 

 substances, some of which possess an acid character, while others are dis- 

 tinctly basic. The bases are represented chiefly by Sodium, Potassium 

 Ammonium, Calcium, Magnesium, Urea, Xanthin, etc., etc., while the 

 chief acids are the following : Hydrochloric, Carbonic, Phosphoric, Sul- 

 phuric (this is also found in combination with aromatic alcohols in form 

 of Ethers), Uric, Oxalic and Hippuric. Besides these bases and acids 

 several kinds of coloring matter are found, together with traces of a sub- 

 stance belonging to the class'of Albumens, and an indifferent substance 

 belonging to the class of Carbohydrates. The two latter are of no im- 

 portance. 



Pathological urine contains besides the normal constituents others of an 

 abnormal character, such as Albumin, Sugar, Biliary coloring matter, 

 Blood, Mucus, Pus, etc. Or the normal constituents may be present in 

 abnormal quantity. 



Specific poisons (Ptomaines, Toxins, etc.) occur in both normal and 

 pathological urine, to a greater extent, however, in the latter. 

 The quantity and quality of the ingested food often leads to an increase 

 of the basic or acid constituents of urine without any pathological sig- 

 nificance. 



The bases and acids present are united in accordance with their chemi- 

 cal affinity and the quantity of each present. Thus a chemical balance 

 is always preserved which under normal conditions is disturbed only by 

 an excessive elimination of certain constituents, such as Uric acid and 

 Urates, causing a precipitate to appear in the urine. 



Reaction. — Normal urine usually reacts acid to litmus paper, as under 

 normal conditions the daily elimination of acids and bases is such as re- 

 sults in the formation of acid salts. The bases are inadequate to neutra- 

 lize all acid, and therefore, besides the normal salts of such acid, acid com- 

 binations also are formed, as, for instance, Sodic dihydric phosphate 

 (NAH 2 P0 4 ). However, not all Phosphoric acid is found in combination 



