518 



Mr. G. S. Johnson. 



and have found differences in the reducing action given by the 

 products. But the specimen which agreed best with the description 

 given by Liebig was destitute of reducing action. 



Professor W. N. Hartley has compared the absorption spectrum of 

 this specimen with that of a specimen of tabular kreatinin <z of urine 

 for me, and his results are published in an Appendix to this paper. 



2nd. The platinum salts differ. 



In all the descriptions of " kreatinin platinic chloride " that I have 

 found, the salt is described as anhydrous. I have subjected the plati- 

 num salt of urinary kreatinin to complete analysis, and find that it 

 contains 2 mols. of water of crystallisation. 



3rd. The solubilities in water and alcohol differ. 



The solubility in alcohol of kreatinin (Liebig) is 1 part in 102 parts 

 of alcohol at 16° C. 



The solubility in alcohol of tabular kreatinin a of urine is 1 part in 

 362 parts of alcohol at 17° C. 



Kreatinin (Liebig) Fdissolves in 11*5 parts of water at 16° C. 



Tabular kreatinin a. of urine dissolves in 10 - 78 parts of water at 

 17° C. 



It appears^therefore, that the tabular kreatinin of urine is slightly 

 more soluble in water, and vastly less soluble in alcohol than the 

 artificial base described by Liebig. 



I will conclude this part of my work by laying stress upon the 

 importance of the precipitation of kreatinin from urine as spherical 

 mercury salt, not only as a convenient method of obtaining the 

 natural base in a state of purity, but also as a means of estimating 

 with accuracy the quantity of kreatinin in a given volume of the 

 secretion ; and at the same time the amount of reduction exerted by 

 the natural base. In Part II will be found an account of the bases 

 obtainable from the kreatin of urinary kreatinin. 



Paet II. 



On the Kreatinins derived from the Dehydration of Urinary Kreatin. 



"When the kreatinin of urine is boiled in dilute aqueous solution in 

 proportion 1 : 1000 by weight of water, it is gradually converted into 

 kreatin, which may be crystallised out by concentrating at the boil- 

 ing temperature. If the first crop of kreatin be separated from the 

 mother-liquor, the latter, diluted largely and again concentrated, 

 yields a further crop of crystals, and this may be repeated as long as 

 any kreatin crystallises out. The whole of the crystals thus obtained 

 are then dissolved together in boiling water, the solution kept boiling 

 with animal charcoal till colourless, filtered, and concentrated. On 

 cooling the pure urinary kreatin crystallises out. 



