282 



Dr. J. L. W. Thudichum. 



[Mar. 18, 



bases with, an alcoholic solution of cerebric acid. Thus, he prepared 

 the insoluble barium compound containing 7'8 per cent, of baryta. 



Bearing this experience of Fremy in mind during my researches on 

 the chemical constitution of the brain, I invariably examined for 

 inorganic ingredients all the educts which I obtained from the'forain.* 



Of Kephalin (the most important of the phosphorised ingredients 

 of the brain) 10 grins, were dissolved in one litre of water, and 

 after nitration precipitated by hydrochloric acid. The solution of 

 hydrochloric acid and other matters filtered from the precipitated 

 kephalin was evaporated to dryness. A portion was then boiled with 

 solution of baryta, when traces of ammonia were evolved. The rest 

 of the residue was then ignited in a platinum dish to destroy all traces 

 of organic matter. The ash was but slightly fusible ; was only par- 

 tially soluble in water, but was easily soluble in water slightly acidified 

 by hydrochloric acid. The solution with ammonia gave an abundant 

 precipitate of earthy salts, and the solution assumed a deep blue colour. 

 Precipitate and solution were separated by filtration. 



The precipitate dissolved readily in a little hydrochloric acid, forming 

 a slightly red solution, suggesting the presence of iron, which was con- 

 firmed by the sulphocyanide test. In another portion of the solution 

 dilute sulphuric acid gave an abundant precipitate of gypsum, showing 

 presence of calcium. In another portion the molybdate test showed 

 the presence of phosphoric acid. To the remaining portion a few drops 

 of ferric chloride were added, then sodic carbonate nearly to neutrality, 

 and, lastly, barytic carbonate. The mixture was allowed to stand, 

 filtered, and the filtrate, free from excess of baryta by sulphuric acid, 

 was again filtered, and the filtrate, after supersaturation with ammonia, 

 gave a great precipitate with ammonic oxalate, showing presence of 

 much calcium. The filtrate from this calcic oxalate on concentration, 

 and treatment with ammonia, ammonic chloride, and sodic phosphate, 

 gave the precipitate characteristic of magnesium. The precipitate 

 produced as above described by baryta carbonate, was boiled with 

 excess of pure soda, and the filtrate was warmed with ammonic 

 chloride; only a slight turbidity ensued, so that it may be assumed 

 that aluminium was absent. 



The alkaline filtrate from the foregoing precipitate by ammonia was 

 tested for lime by oxalate, when a considerable precipitate was pro- 

 duced, showing the presence of lime uncombined with phosphoric acid, 

 and which therefore must have been in combination with part of the 

 kephalin. The blue solution was again filtered from calcic oxalate, 

 which had been entirely precipitated, and was acidified with hydro- 

 chloric acid. The copper was precipitated by hydrothion, the filtrate 



* That part of my experience relating to kephalin and myelin is recorded in " Re- 

 ports of the Medical Officer of the Privy Council and Local GrOTernment Board," 

 new series, JSo. Ill (1874), p. 129, and ibid., No. Till (1876), p. 131. 



