into a substance isomeric with Cellulose and Inuline. 13 



gummy substance, having a composition identical with that of 

 gum-arabic. This is remarkable, inasmuch as it affords an 

 instance of what may be called a retrograde chemical action, 

 the sugar being converted into dextrine, — a change similar 

 to that which occurs in fruits when they lose their sweetness, 

 and assume that condition commonly called " sleepy." The 

 conversion of cellulose into dextrine and sugar seems to be a 

 process of continual occurrence and great importance in the 

 vegetable ceconomy, but we are not aware of any example of 

 the reverse of this action, except those instances mentioned 

 above ; in the former of which sugar is converted by fermen- 

 tation into a body having all the properties and composition 

 of gum ; in the latter, the sugar being changed into cellulose*. 

 We therefore consider the observation we are about to describe 

 to be possessed of some interest, as affording another case of 

 a similar retrograde action. It has been observed that the 

 effervescing drinks known as lemonade, gingerade, &c, made 

 by forcing carbonic acid gas into solutions of sugar variously 

 flavoured with tartaric acid and essential oils, in certain cases 

 lose their fluidity, and assume a thick, slimy consistence. 

 When the bottles containing these thickened liquids are 

 opened, the expansion of the carbonic acid expels their con- 

 tents with difficulty, owing to their extreme tenacity. In- 

 stances of this change are of continual occurrence, all the 

 manufacturers of whom we have inquired having observed it 

 when the bottles had been kept for some time. Various opi- 

 nions have been expressed by them as to the cause of the con- 

 version, but it seems to occur invariably when the liquor is kept 

 long enough. We are indebted to Mr. Baildon of this city 

 (Edinburgh) for an opportunity of examining a sample of 

 gingerade, in which this thickening had occurred. This liquid 

 is made by sweetening an infusion of ginger-roots with cane- 

 sugar, and flavouring it with oil of lemons and tartaric acid ; 

 this is then placed in bottles, and carbonic acid forced by pres- 

 sure into the fluid. Another manufacturer uses the following 

 ingredients in the preparation of effervescing lemonade: — 

 2 ounces of honey, 4 pounds of sugar, 2 ounces of citric acid, 

 2 drachms of oil of lemons and I| ounce of bicarbonate of soda. 

 According to the opinion of this manufacturer, the change 

 occurs chiefly in winter, when the liquid is exposed to cold, 

 and he thinks that the addition of a double proportion of honey 

 tends to prevent it. To separate the substance to which the 

 viscidity was owing, the contents of a bottle were digested with 

 six or seven parts of alcohol, under the action of which the 

 gummy matter consolidated, and when dried became so hard 

 * See Mulder's All. Phys. Chem., p. 243 ct seq. 



