S36 Avalysh of the CereLral Matter of Man, [May^ 



effect in the entire brain were removed by the alcohol. We shall 

 see hereafter what these constituents are. 



Sect. IV. 



Examination of the fatty matter of the Irain which is depo^ 

 sited during the cooling of the alcohol in which brain has been 

 boiled. 



We have already described the principal physical characters of 

 this substance : we have said that it was white and solid, but soft, 

 and of a pitchy consistence ; that it had a brilliant and satinlike 

 aspect ; and that it stained paper in the same manner as oils do. 

 We shall now examine its chemical nature and composition. 



1 . When exposed to heat it melts, but it does not become so 

 fluid as tallow does, and assumes a brown colour at a temperature 

 at which common fat is not altered. 



2 It dissolves in hot alcohol, leaving only a few flocks of 

 animal matter, which had been dissolved in the first operation 

 by means of the water contained in the brain. During the 

 cooling of the alcohol the greatest part of this matter precipi- 

 tates with all its usual characters : 20 parts of alcohol at S6 de- 

 grees are sufficient to dissolve one part of this matter. 



3. When exposed to the sun this matter acquires a yellow 

 colour, nearly similar to that of the fatty matter which is 

 obtained by the evaporation of the alcohol, after it has deposited 

 the fatty matter, the properties of which we are describing. I 

 do not know the reason of this phenomenon. 



4. A portion of this matter, which had been dissolved several 

 times in alcohol to separate the last remains of the animal matter 

 which it contained, was burnt in a platinum crucible. The 

 combustion took place very readily, and was accompanied by a 

 great deal of flame and smoke. The charry residue washed with 

 distilled water communicated to that fluid a very distinct acidity^ 

 and the property of precipitating lime-water. 



The singular result of this operation, which announced un- 

 ambiguously the presence of phosphoric acid, made me suspect 

 that tliis fatty matter contained phosphoric acid, or phosphate of 

 ammonia, the base of which might have been volatilized by heat, 

 though this last opinion was not very probable. However, to 

 (determine the point, I made the following experiments : — 



1 . I mixed the fatty matter with distilled water, and observed 

 with surprise that it formed with that fluid a kind of emulsion, 

 and did not separate from it. Ai the same tim.e, I observed that 

 this emulsion possessed no acid properties, and did not alter the 

 colour of tincture of litmus. 



2. I mixed it with a solution of caustic potash, and perceived 



