510 



Mr. G. S. Johnson. 



Kequired. Found. 

 Oxygen 5-017 .... 4*340 (By difference) 



Platinum... 30-878 .... 3V047 f ' ' ' 



J 30-98' 

 { 31-11 



Chlorine .... 33*385 .... 33-333 



100-000 100-000 



The above being the formula of the anhydrous platinum salt of the 

 reducing base of urine, it appears that the formula of the orange- 

 coloured prisms obtained by spontaneous evaporation of the aqueous 

 solution, is 2(C 4 H 7 N 3 O.HCl).PtC] 4 .2H 2 0. This formula requires 

 5' 34 per cent, of water of crystallisation, whilst the mean of the three 

 determinations given above indicates the presence of 5'32 per cent. 



Preparation and Properties of the Reducing Base — Kreatinin of Urine. 



The reducing base or kreatinin of urine is obtained in the free state 

 by treating the concentrated aqueous solution of its hydrochloride 

 (prepared as above from the spherical mercury salt) with excess of 

 very pure hydrated lead oxide at the ordinary temperature. 



The crystallised hydrochloride should be dissolved in about fifteen 

 times its weight of cold water, and an excess of perfectly pure recently 

 precipitated lead hydrate added to the solution, which should be kept 

 stirred constantly for about twenty minutes at the ordinary tempera- 

 ture. After the liquid has acquired a strongly alkaline reaction, it 

 will be found to filter clear through paper. The filtrate is perfectly 

 free from chlorine and colouring matter, and yields the urinary 

 kreatinin on spontaneous evaporation in vacuo over sulphuric acid in 

 the crystalline condition. It is better not to dilute the filtrate by 

 adding the washings from the lead oxychloride to it, but these may 

 be evaporated separately by heat.* 



The same sample of the spherical mercury salt of the urinary 

 kreatinin may be made to yield three different substances according 

 to the treatment adopted in the separation of the kreatinin from it. 

 The following details of an experiment conducted upon the large 

 scale will best exemplify this statement. 



260 grams of the spherical mercury salt of the urinary kreatinin 



* The lead hydrate employed, for liberating the reducing kreatinin of urine from 

 its hydrochloride must be free from basic lead nitrate. When this compound is 

 present, the alkaline filtrate, though free from chlorine, is found to hold in solution 

 both lead and the radicle of nitric acid ; moreover, the lead cannot be removed from 

 solution by animal charcoal, even at the boiling temperature, but must be separated 

 by hydrogen sulphide, after which the. filtrate from the lead sulphide exhibits an 

 acid reaction, and deposits crystals of kreatinin nitrate on evaporation. 



I have found it best to employ lead hydrate precipitated from the acetate by 

 ammonia. 



