3^0 Exjeriiiioils en Sugijr.^~Its Convcrficii into Gum. 



whicli \vc conceive mull proceed from the deeompofition of the water, whofc oxygene unitcj 

 with the carbonaceous principle of the barley, whilll its iiydrogene is fixed, and may be ne- 

 ccflary to the produdiou of the faccliarine principle. We fuppofc, therefore, that vegetable 

 mucilage is converted into fiigar by being deprived of part of its carbonc, whilft at the fame 

 time it is combined with a greater proportion of oxygene, and probably alfo with Iiydrogene 

 from the deeompofition of tlic water. TJius, then, both from anaiyfis and fynthefis, it would 

 appear that fugar contains more oxygene tlian gum or mucilage. P'rom this hypotliefis it 

 fliould follow, that if fugar be deprived of part of its oxygene, it muft lofe its fwcetncfs, 

 and form fomething like a gum. To fee how fir this might be accoinpliflied was the object 

 of the following experiments: 



A quantity of fyrup was introduced into a jar, filled with, and inverted over, mercury : 

 to this was admitted about an equal quantity of the phofphuret of lime: a confiderable pro- 

 duftion of phofphorie gas almoll immediately took place, and the mercury defcended in the 

 jar. At the expiration of eight days the fyrup was withdrawn and examined : it had no 

 fenfibly fweet tafte, but rather a bitter aftringent one : when filtered, alcohol produced a 

 copious white precipitate in flakes, very much rcfembling mucilage feparated from water by. 

 the fame fubftance. 



This experiment was fomewhat varied, as follows: A little refined fugar wasdilTolved in 

 alrnliol, and to this folution a little phofphuret of lime was added : no phofphorie gas was 

 difcnpagcd, nor was there any apparent aflion produced. More phofphuret being added, 

 die mixture was allowed to remain in an open phial for feveral days. The alcoliol having 

 now evaporated, feme dillliied water was added ; but this- produced no difengagemcnt of 

 gas, as the phofphuret had been deeompofcd, and converted principally into pliofphatc ol 

 lime. The mixture being filtered, and the clear liquor evaporated, there remained a fub- 

 flance extremely tenacious, and which had much the appearance of gum-arabic : its tafte 

 >ras bitter, \yith a very, flight degree of fweetnefs : when fquee/.ed between the teeth it had 

 cxaftlv the feel of gum, but more tenacious. It did not appear to be foluble in alcohol, 

 or iit leall in any confiderable quantity : when thrown upon a red-hot iron it burned like 

 g<ini, and left a bulky and infipid charcoal. 



It would appear that the faccharine principle had been deftroyed in thefc experimentSj 

 and converted into fomething refenibling a gum. That this was effefted by tlie abdraclion 

 of oxvcne is rendered highly probable from the nature of the fubftance employed, and the 

 change wliieli it was found to have undergone ; for there are few fubflances which have fo 

 Hrong a tendejicy to combine with oxygene as the phofphuret of lime. 



Some other trials o: a fimilar nature were made by mixing folutions of fugar with the 

 (HifFerent fulphurets, aftd by agitating them with nitrous gas in cIofevetTels. The fulphurets, 

 more efpecially that of pot-afli, manifeftly deftroyed tlic faccharine tafte; but on account of 

 iht folubility of the different products, the particular change produced could not be fo cafily 

 ^u^a^eurat^lyufcertained. The ailion of the nitrous gas was more doubtful. 



In order to be fatisfied how far the etTecls produced on the fugar in the former experl- 

 roc.nts might be owing to the abftradlion of oxygene, I added to folutions of this fubftance 

 ilt 'water both lime and pure pot-afli, and boiled the mixtures for fome time : the lime ap- 

 peared, raanifcllly to combine with tlie fugar, to which it communicated a very bitter af- 

 tringcnt tafte, but it was ftill fweet : a little alcohol, added to the filtered folutions, pro- 

 duced 



