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Mr. G. S. Johnson. 



[June 16, 



The author found that about three -fourths of the total reducing 

 action of normal urine is destroyed by prolonged boiling with potas- 

 sium hydrate, the remaining one-fourth being due to the survival of 

 the uric acid, thus confirming Dr. Pavy's observation that one-fourth 

 of the normal reducing action is due to uric acid. 



On attempting to isolate the normal reducing agents by precipitant s, 

 it was found that mercuric chloride gradually effected complete pre- 

 cipitation of the reducing agent when added in sufficient excess to 

 the unconcentrated urine. Complete precipitation can be effected in 

 forty-eight hours if one-twentieth of its volume of a cold saturated 

 solution of sodic acetate be first added to the fresh urine, then one- 

 fourth of its volume of a cold saturated solution of mercuric chloride. 

 The precipitate, which forms immediately, should be separated by 

 filtration, as it contains no reducing agent except uric acid, which 

 is probably present in it as mercuric urate ; but the filtrate from the 

 first amorphous precipitate begins to deposit the mercury salt of the 

 reducing base in about half an hour. This deposit appears granular 

 and crystalline, but under the microscope is found to consist of 

 minute spherical masses. The weight of the dry spherical precipitate 

 is always greater than that of the amorphous one weighed in the same 

 condition. The desiccation must be conducted over sulphuric acid at 

 the ordinary temperature, since the compound is decomposed at 100° C. 

 in presence of water. 



The filtrate from this granular (spherical) mercury salt is devoid 

 of reducing action upon cupric oxide and picric acid. The spherical 

 mercury salt of the reducing base (for the basic nature of the normal 

 reducing agent is strongly indicated by the above results) is easily 

 soluble in hydrochloric acid, but insoluble in acetic acid. Moistened 

 with solution of potassium hydrate, the compound gradually blackens 

 from reduction of mercury at the ordinary temperature, and much 

 compound ammonia is evolved. Suspended in cold water and treated 

 with hydrogen sulphide, the compound is decomposed, mercuric sul- 

 phide remaining undissolved, whilst the solution becomes acid in 

 reaction, and exhibits reducing properties. On evaporating this 

 acid solution a crystalline salt is obtained, which is the hydrochloride 

 of the reducing base. As the spherical mercury salt, obtained as 

 above from urine, appeared to be always quite homogeneous and 

 pure, with the exception of a little colouring matter, the exact weight 

 of the compound obtained from known volumes of urine was next 

 ascertained. 



The samples of urine examined were in all cases ascertained to be 

 free from albumen and sugar before precipitation. The filtrates from 

 the first or amorphous precipitate, produced by mercuric chloride and 

 sodic acetate, were allowed to collect in a large glass vessel, in which 

 the spherical compound gradually accumulated. After standing 



