166 On the Liquid Gum [March, 



The aqueous solution remains muddy, even after standing for 

 weeks 5 but by repeated filtrations, or by mixing it with hot 

 water, it may be obtained transparent. 



When a drop of water is let fall upon the liquid gum, the 

 spot on which it lights becomes lighter coloured, as if the solid 

 matter consisted of two distinct substances ; one, dark coloured, 

 more soluble in water; and the other light coloured, and less 

 soluble: but 1 found it impossible to procure any two such 

 substances in a separate state, either by means of water, or any 

 other re-agent. 



The aqueous solution of our liquid gum is of a dark red 

 colour inclining to brown ; its taste is the same with that of the 

 gum ; and when evaporated to dryness, it leaves behind it a 

 substance precisely the same as the solid residue procured by 

 exposing the liquid gum to the open air. 



Alcohol is the proper solvent of our liquid gum ; taking it up 

 very readily, both in its natural state, and when deprived of its 

 water by evaporation : but the solution takes place much more 

 readily in the first than in the second state. 



Alcohol of the specific gravity of 0 (SOO easily takes up half its 

 weight of the gum. The solution is blood coloured, and so deep 

 as to be opake; but a drop or two put into a phial of alcohol 

 gives the whole a beautiful crimson colour. 



The solution has an astringent taste, and may be diluted wjth 

 water without any precipitation. Indeed, the addition of alcohol 

 to the muddy aqueous solution makes it transparent, and prevents 

 all subsidence. 



3. Sulphuric ether is slightly coloured by the gum, but dis- 

 solves only a very small portion of it. 



Thus it appears that the so called liquid gum is a compound of 

 44 parts solid matter and 56 water ; that it is soluble both in 

 water and alcohol, and weak spirits. Jt remains for us to ascer- 

 tain the properties of the solid matter. For this purpose \ 

 exposed the aqueous solution to a variety of chemical agents. 

 Tiie following are the most important facts. 



I. Action of Glue, 



When a solution of glue is mixed v/ith the aqueous solution of 

 pur gum, the mixture becomes immediately filled with flesh 

 coloured flashes, which gradually subside, leaving the solution 

 jcolourless. If the glue has been cautiously added, as long as 

 any precipitate fall the whole gummy matter of the so called 

 gum is separated ; for when the liquid is evaporated to dryness, 

 nothitig is obtained but a little glue. When the flesh coloured 

 precipitate thus obtained is dried, it becomes brown, and bears a 

 ^trong resemblance to the precipitate thrown down from catechu_, 



