ON VEGETABLE MUCILAGES* - 39 



liow6Vcrr, in which it is usually procured, it seems to be a 

 compound of two or more of the \«e,^et able principles. A 

 quantity of starch is obviously mixed with it ; and I am in- 

 clined to think, that it also contains gluten, a supposition 

 which will account for all the phenomena it exhibits with 

 the chemical reagents. 



There are two substances, the characters of which still Cheny gum, 

 remain to be ascertained, cherry gum and tragacanth. From 

 its physical properties we should be disposed to place cherry 

 gum in the same class with gum arabic ; but it is so differ- 

 ently affected by the chemical reagents, as absolutely to pre- 

 vent us from considering it in this point of view. Its pro- 

 perties are not more characteristic of mucus ; nor does it af- 

 ford any indications of being a compound substance, so that it 

 may probably be necessary to consider it as a distinct veget- 

 able principle. The action of the acetate of lead and of al- tinci^principle* 

 cohol upon cherry gum would induce us to suppose, that it 

 bore an analogy to sugar, rather than to the gums or mu- 

 cuses ; but the effect of the nitro-muriate of tin is not fa- 

 vourable to this supposition ; nor is that of the nitric acid, 

 which I found, by the usual process, converted it principally 

 into the saclactic acid. If we are to bestow a new name 

 upon it, we might denominate it cerasin. Cerasin. 



I am equally unable to determine in what class traga- 

 canth ought to be placed. It has obviously no relation to Tragacanth. 

 gum, either in its physical or chemical properties ; and it 

 differs very considerably from what has been laid down as 

 the generic character of mucus. Its properties are the most 

 similar to those of starch and gluten ; particularly to that 

 form of starch, which is prepared by first forming it into a 

 mucilage with hot water, and then evaporating it to dryness, 

 when it becomes transparent and brittle, but almost insoluble 

 in water. The effect of the nitro-muriate of gold forms a 

 remarkable character of tragacanth mucilage ; it seems to 

 depend upon a partial reduction of the oxide, at the same 

 time that it unites with the tragacanth. The effect was very 

 evident when the solid matter composed 1-50 part of the 

 fluid, but if much more diluted, it was not perceptible ; a 

 slight degree of the same effect is produced when the nitro-i 

 muriate of oold is added to flour paste. 



I am 



