On Kreatinins. 



521 



have been unable to ascertain the cause of the formation of these two 

 bodies in different experiments, but I shall show presently that they 

 are very easily convertible the one into the other. 



For the cry stallo graphic examination of the kreatinin crystals pre- 

 pared by me from urine and from the kreatin of urine, I am indebted 

 to the kindness and patience of Mr. L. Fletcher of the Mineralogical 

 Department of the British Museum. He has found that the tabular 

 crystals of kreatinin, both natural and artificial, are identical in their 

 angles with those measured by Kopp and Heintz. He has also made 

 for me (with the aid of Mr. H. A. Miers) what, I suppose, are the 

 first measurements of the efflorescent kreatinin. Mr. Fletcher's 

 report is as follows : — 



Kreatinin (measured by Fletcher). 



Anhydrous tabular K. from urine and from urinary kreatin by 

 Liebig's process. Thin, rectangular, nearly square tables. 



System — Monosymmetric. 



Elements— a :b:c:: 1'235 : T116 ; y = 69° 47'. 

 Forms observed— a{ 100}, c{001}, m{H0}, ^{101}. 



The development of the forms is illustrated by Figs. 2 and 3. 

 The form d was only observed in one of the crystals. 

 There is an easy cleavage parallel to a 1 {100}. 



Fig. 2. 



Fig. 3. 





Observed. 













Kopp. 



Heintz. 



Angles. 



Mean. 



Limiting values. 







ac. . . . 



69° 47' 



69° 35'— 70° 3' 



69° 24' 



69° 57'— 70° 30'. 



cd Y . . . 



50° 58' 



50° 50'— 51° 6' 







am . . . 



49° 13' 



48° 48'— 49° 34' 







mm x . . 



81° 34' 



81° 12'— 81° 53' 



81° 40' 



81° 40', sometimes 37' or 38'. 



