44 Analyses of Books. [Jan. 



•when mixed with the aqueous solution of iodine, and presents 

 with this re-agent all the effects of starch. It is coagulated into 

 a white paste by the subacetate of lead ; but not by the neutral 

 acetate. It is copiously precipitated by barytes water, but not 

 by lime water, nor decoction of nutgalls. It dissolves in the 

 aqueous solution of potash. This liquid is very fluid, and wants 

 the viscidity of the solution of starch in potash. The weak acids 

 precipitate the aniylin from it with all its properties. Alcohol 

 likewise throws down a copious precipitate, which, however, 

 retains a portion of the alkali, and does not strike a blue with 

 iodine till an acid is added to it. 



The starchy lignin was obtained from the residue of the spon- 

 taneous decomposition of starch, after that residue had been 

 deprived of every thing soluble in cold water, hot water, alcohol, 

 and very dilute sulphuric acid, by digesting it in 10 times its 

 weight of an alkaline ley containing one-twelfth of its weight of 

 potash. A brown liquid solution is obtained, from which dilute 

 sulphuric acid precipitates the starchy lignin under the form of a 

 brown, light combustible substance, having the lustre of jet. It 

 gives a blue colour to the aqueous solution of iodine. This last 

 property, together with its solubility in a weaker alkaline ley, 

 distinguishes starchy lignin from common lignin. 



During the spontaneous decomposition of starch, the bulk, 

 of the air undergoes no change ; but a small portion of its 

 oxygen is slowly converted into carbonic acid gas. Fifteen 

 grammes (231a gr. troy) of starch mixed with 12 times its weight 

 of water produced in two months, in the temperature of 12-^'^y 

 only 50 cubic centimetres (19"68 cubic inches) of carbonic acid 

 gas. Thus the action of the oxygen of the air is confined to the 

 abstraction of carbon. The loss of weight which the starch 

 sustains is much greater than can be accounted for by the carbon 

 abstracted by the oxygen of the air. Hence the starch must lose 

 a considerable portion of its weight by giving out oxygen and 

 hydrogen under the form of water. 



To ascertain the difference in the result when the starch was 

 allowed to decompose in the air and in a vacuum, the experiment 

 was repeated both ways for 38 days in a temperature of about 

 72-}°. The following table exhibits the results of these two 

 experiments : 



One hundred parts of starch decomposed without the contstet 

 of air, yielded 



Sugar 47*4 



Gum. 23-0 



Alylin 8-9 



Starchy lignin 10^2 



Lignin mixed with charcoal Trace 



Starch not decomposed » 4-0 



93'Q 



