1820.] Philosophical Transactions for \%\^, Part I. 43 



The sugar possessed the characters of the sugar made from 

 starch by means of sulphuric acid. 



The gum possessed the following properties : It was transpa- 

 rent, and almost colourless, when formed without the contact of 

 air ; but when the starch became covered with mucors, the gum 

 was yellow, and rather too soft to be reduced to powder. One 

 hundred parts of this gum at 66°, when exposed to the heat of 

 212°, lost 11*75 of their weight. It does not absorb moisture 

 from the air, nor is it altered by exposure to the atmosphere ; but 

 its aqueous solution becomes gradually putrid, depositing a thick 

 mucous matter. It is insoluble in alcohol, but soluble in water 

 in every proportion. Two parts of water and one of the gum 

 form a very fluid solution, but it becomes viscid and thready 

 when the weight of the gum exceeds that of the water. A 

 solution of one part of the gum in ten parts of water is neither 

 precipitated by acetate of lead, nor subacetate of lead, nor the 

 decoction of nutgalls, nor sihcate of potash. It does not alter 

 the colour of the infusion of htmus. It does not alter the colour 

 of aqueous solution of iodine. It is shghtly precipitated by 

 barytes water. It does not form mucic acid when treated with, 

 nitric acid. It possesses most of the characters of the gum into 

 which starch is converted by roasting. 



Saussure has applied the term amidin to a substance which he 

 considers as intermediate between gum and starch. The word 

 is formed from the French term amidon (starch). As it is con- 

 trary to rule to permit the nomenclature of chemistry to be 

 obscured by words borrowed from living languages, it is obvious 

 that if a new term be requisite for this substance, we must call 

 it amylin (from the Latin word anuilam), used by the moderns 

 for starch. It is obtained from the residue left by the sponta- 

 neous decomposition of starch after it has been treated with a 

 sufficient quantity of cold water to dissolve every thing soluble 

 in that liquid. Boiling water dissolves the amylin, and it may 

 be obtained by evaporating the solution to diyness. It is 

 obtained either in irregular, opaque fragments, or of a yellow- 

 pale semitransparent brittle substance, according to the mode of 

 -conducting the evaporation. It is insoluble in alcohol. Cold 

 water dissolves about one-tenth of its weight of it, and forms a 

 colourless and very fluid liquid. Water of the temperature of 

 144° dissolves it in any proportion, and retains in solution, after 

 cooling, a much greater proportion than can be dissolved in cold 

 water. The decoction may be concentrated till it contains one- 

 fourth of its weight of amylin in solution without becoming 

 muddy or gelatinizing on cooling, which is not the case with 

 starch. \Vhen the liquid is more concentrated, the amylin pre- 

 cipitates in part on cooling in the state of a white opaque matter; 

 but It is redissolved on heating the water to 144°, In this 

 respect it approaches inulin. The solution of amylin containing 

 one-tenth of its weight of this substance, assumes a blue colour. 



