Gum, Sugar, avd an Acid, ly means of Sulphuric Add, t^c. 119 

 reagents cannot indicate. The residum shows after incineration 

 some traces of sulphate of lime. 



When this gum is exposed with potash to the fire to decom- 

 pose it partially, no sulphurous acid is disengaged. If the re- 

 siduum is dissolved in water, and nitric acid added, a brown floc- 

 culent matter is precipitated, which is known more particularly 

 hv the name of artificial ulmine. If nitrate of barytes is added 

 to the filtered liquor, it produces a precipitate of sulphate of 



barvtes. ^ , j • u i. 



The solution of this gum in water is not disturbed either by 

 nitrate of barvtes or by acetate of Tead ; but the sub-acetate of 

 lead produces a verv white and abundant magma entirely soluble 

 in weak acetic ai;id. If the lead which the liquor above this 

 precipitate contains is precipitated by carbonate of ammonia, 

 «nd then evaporated to drvness, the residuum is a triple combi- 

 nation of gum, acetic acid, and ammonia. The hydrochlorate 

 of the protoxide of tin also precipitates this gum from its dissol- 

 vent. Lime water or barytes in excess produces slight flocculent 

 precipitates, which are nothing but combinations of gum with 

 lime or barytes. The red sulpliate of iron does not affect in the 

 least the solution of this gum, while it coagulates abundantly 

 that of gum arahic. Treated with sulphuric acid, this gum fur- 

 nishes a large quantity of oxalic acid in fine crystals, but no 

 mucous acid. 



Sugar from Liucn. 

 The gummy matter the properties of which we have mentioned, 

 being boiled for some time with diluted sulphuric acid, experi- 

 ences such a change of ecjuilibrium in the nature of its principles, 

 that in separating thev produce two very remarkable substances: 

 the one which forms almost the whole of the matter is crystalh- 

 zable sugar; the other contains the elements of the sulphuric 

 acid which were disseminated in the gummy matter, and consti- 

 tutes a singular enough acid, which I will designate under the 

 name of the vei^eto- sulphuric acid. I was led accidentally to 

 this result, bv treating a solution of t!ie acid mucilaginous mass, 

 produced bv'the action of the sulphuric acid on linen, with the 

 oxide of leJ<l, subjected to a long continued heat of 100" centi- 

 grade ; but after having passc.l through the liquor a current of 

 sulphurated hvdrogen gas to precipitate the lead contained in so- 

 lution, and after evaporating it, I was agreealily surprised to see 

 that the whole of the guminv matter was entirely converted into 

 ail acid sugary mass. I digested this mass with very concen- 

 trated alcohol; by which the vegeto-sulphuric acid was dissolved : 

 the bugarv matter remained a little coloured, and of a very fresh 

 flavour. * Twenty-four grammes (370-r. gr.) of old cloth «-cll 

 114 dried, 



