88 BRAIN . 



remain undissolved. To the boiling solution add 

 neutral acetate as long as any precipitate is produced. 

 Filter. 



13. The precipitate may contain lead urate as well 

 as lead, salts of inosic and similar acids. Suspend in 

 a moderate quantity of water and decompose by 

 sulphuretted hydrogen. The lead sulphide will retain 

 most of the uric acid, which may be extracted by 

 boiling with water, while the filtrate will contain the 

 inosic acid and allied bodies, if present. 



14. The filtrate from the precipitate by neutral lead 

 acetate must be precipitated by basic lead acetate 

 and cupric acetate. The solution filtered from these 

 precipitates may contain tyrosine, which must be iden- 

 tified by evaporating, dissolving the crystals or deposit 

 in a little hydrochloric acid, precipitating by sodium 

 acetate, and applying the mercury nitrate and nitrite 

 test. (See Tyrosine). 



15. The precipitate may contain xanthine, hypo- 

 xanthine, and inosite. Suspend the precipitate in a 

 rather large quantity of water, decompose by hydro- 

 thion, filter, extract the lead sulphide with boiling 

 water and evaporate the filtrate and extract together 

 to dryness. From the residue extract the inosite by 

 cold water, and purify by crystallisation. The re- 

 maining xanthine and ImjpoxantJiine may be separated 

 and purified by the processes described under those 

 bodies. 



16. Burn a portion of dried mixed brain-matter care- 

 fully in a platinum dish (best in a muffle) and analyse 

 the ash, noticing that there is always a quantity of 



