CHAP. III.] PHYSICAL PROPERTIES OF TYROSINE. 



249 



From very impure solutions it separates in part or wholly in 

 nodules and balls very similar to.those of leucine. 



Crystallisations of pure tyrosine often present, to the naked eye, 

 a white opaque paper-like appearance due to the aggregation of 

 crystals. 



FIG. 16. CRYSTALS OF TYROSINE. 



Tyrosine is soluble in about 1900 parts of water at 

 ordinary temperature, and in 150 parts of boiling water ; 

 it is insoluble in alcohol and ether. 



Tyrosine is readily soluble in solutions of ammonia, in solutions 

 of the caustic alkalies and their carbonates. It is likewise soluble 

 in dilute concentrated mineral acids, with which it forms somewhat 

 unstable compounds. 



Compounds Tyrosine forms a compound with hydrochloric acid, 



of tyrosine. C 9 H n N0 3 . HC1 + 2H 2 0, which is easily soluble in abso- 

 lute alcohol, but is split up by water into tyrosine and hydrochloric 

 acid. Similar compounds with nitric and sulphuric acids have been 

 obtained. 



Compounds of tyrosine with sodium, calcium, barium, silver and 

 mercury exist and have been more or less completely investigated 1 . 

 The compound of copper with tyrosine deserves special mention, 

 on account of its sparing solubility. It is obtained by boiling solu- 

 tions of tyrosine with freshly precipitated cupric hydrate, and sepa- 

 rates in the form of small, dark blue, shining needles which are soluble 

 in 1230 parts of cold and 240 parts of boiling water, but are insoluble 



1 Consult Lehrbuch der Zoochemie von Prof. Karl B. Hofmann, Wien, 1879, p. 15. 



