;d6 



ON VEftF.TABLE MUCILAGES. 



Silicated pot 

 ash. 



Tan. 



AloohQl. 



Nitric acid. 



hyacinth mucilage, and in the flour paste, and still more re-* 

 inarkably in the ghiten ; there is a slight precipitate in the 

 linseed, and a coagulation in the quince, but no change of 

 colour. The silicated potash acts only upon gum arable, and 

 points out its presence when it exists only in a very minute 

 quantity. Tan does not act upon any of the mucilage^, ex- 

 cept in a slight degree upon tragacanth ; it is copiously pre-' 

 cipitated by gluten, and also by vegetable jelly. The eifects 

 of alcohol have been fully stated. Gum arabic it precipitates 

 from the water in such a manner as to render the fluid com- 

 pletely opake ; whereas in the linseed, quince, and traga- 

 canth mucilages, the solid matter was separated in a fibrous 

 form; with the hyacinth mucilage both the pulverulent and 

 fibrous kinds of precipitate were produced ; while the cherry 

 gum was only slightly affected by it. Alcohol precipitated 

 starch in the same manner that it did gum arabic, 



The action of the nitric acid on the different mucilages 

 was so similar, as not to exhibit any phenomena, which can 

 assist us in distinguishing them from each other. Accord- 

 ing to the circumstances of the process, either the saclactic 

 acid, or a mixture of this acid and the oxalic was produced, 

 attended with the usual disengagement of gas. It did not 

 appear, that any use can be made of the sulphuric acid as a 

 test of the differejit mucilages ; I put in practice the process 

 mentioned by Ilermbstaedt, for separating gum from muci- 

 lage, but in no instance did 1 perceive the coagulation whieh 

 he describes. The acid, in a concentrated state, slowly dis- 

 solves the different mucilages, and forms with them a thick, 

 black fluid. I did not observe any effect to be produced by 

 Neutral sajts. the addition of the neutral salts, except that many of them 

 Alkalis coagulated the quince mucilage. The pure alkalis gene* 



rally rendered the mucilages more fluid, but they did not 

 exhibit any specific or discriminating effect, 



. _ . Before we attempt to make any arrangements of the ve- 



Arrangfiment ^ •■ ^ , ■^ ~ 



of the vegeta- getable mucilages, it is necessary to inquire, whether the 

 lie mucilages, different varieties are to be considered as all of them homo-- 

 geneous, or whether at least some of them ought not to be 

 regarded as compounds of two or more of the primary niuci- 

 Some of the ^^r,^^' Although I am not acquainted with any method, by 

 compounds, which the constituent parts of the compounds can be sepa^ 



rated 



Sulphuric 

 acid. 



