92 



several days until putrefaction had commenced. The fluid was then 

 filtered so as to separate the insoluble albuminous flakes, and the 

 clear liquid heated in a water-bath with the blue oxide of copper ; 

 when, instead of the suboxide being produced, the black anhydrous 

 oxide was formed, just as is the case when the blue oxide is heated 

 merely with water, thus satisfactorily showing that the reducing 

 substance had been destroyed. 



The recent investigations of Virchow* and Buskf have shown 

 that substances of a non-nitrogenous nature exist both in the brain 

 and spinal cord, but they hold somewhat different opinions respect- 

 ing their exact characters ; for whilst the former considers them to 

 be cellulose, the latter regards them both in their " structural, che- 

 mical and optical properties " to resemble starch. In conformity 

 with these views, it was interesting to determine if any indications 

 of the presence of either of these substances could be found in the 

 cerebro-spinal fluid ; accordingly a portion of the fluid was evapo- 

 rated nearly to dryness and then divided into two portions ; to one 

 was added an alcoholic solution of iodine and concentrated sulphuric 

 acid, when a violet tint was produced, which after a few minutes dis- 

 appeared ; but it was also found that this same appearance was pro- 

 duced when the acid and iodine solution were mixed together alone, 

 the violet colour being evidently owing to the volatilization of a part 

 of the iodine and the evolution of its characteristic violet tint; to 

 the other a solution of iodide of potassium and then nitric acid was 

 added, when a brown colour was produced, owing to the liberation 

 of the iodine. In neither portion could it be said that any evidence 

 of the presence of starch or cellulose was detected. 



A comparative trial was also made between the effects produced 

 upon the blue oxide of copper by the cerebro-spinal fluid, solutions 

 of grape-sugar, cane-sugar, starch, cellulose, and mannite, an unfer- 

 mentizable sugar. These various substances were heated in a water- 

 bath for the same length of time, when it was found that whilst the 

 grape-sugar effected a reduction immediately, and the cerebro-spinal 

 fluid only after the lapse of several minutes, neither the starch, cellu- 

 lose, cane-sugar nor mannite effected any reduction at all. 



The power of reducing the blue oxide of copper is not confined to 



* Quarterly Journal of Microscopical Science, January 1854. f Ibid. 



