BRAIN. 87 



slightly acidified with sulphuric acid. Mix the ethereal 

 solution with water, distil off the ether, remove any 

 sulphuric acid by cautious addition of baryta water, 

 evaporate the filtrate and test for lactic acid (q. v) by 

 the zinc salt, and for urea. 



10. The part insoluble in ether must be diluted with 

 water, freed from sulphuric acid by addition of just 

 sufficient baryta water, the nitrate evaporated to a low 

 bulk and exhausted with boiling absolute alcohol. 

 Leucine, kreatine, and urea will dissolve, and some leu- 

 cine may crystallise out on cooling. From the alcoholic 

 solution expel the alcohol by distillation till the aqueous 

 residue forms not too thick a syrup, adding a little 

 water, if necessary, and set aside to crystallise. 

 Kreatine and leucine will separate while urea will 

 remain in the mother liquor, and may be isolated by 

 nitric or oxalic acid. (See Urea). 



11. The kreatine and leucine may sometimes be 

 mechanically separated (the former being in crystals, 

 the latter in opaque granules) and afterwards be 

 purified by crystallisation from alcohol. If not, 

 dissolve the mixed deposit in hot water, and boil with 

 zinc chloride. On cooling and standing, kreatinine, 

 zinc chloride, and kreatine will separate in granules 

 (see those bodies) . From the liquid after precipitation 

 of the zinc with ammonium carbonate and boiling, and 

 evaporation of the filtrate, leucine (and homologues) 

 may be isolated by the process given under leucine 

 (q.v.). 



12. The portion insoluble in boiling alcohol must 

 be exhausted with boiling water. Some uric acid may 



