412 Mr Brown on the Mucilage of the Fuci. 



780 ill a thousand parts of this mucilage, or, as he styles it, 

 " albumen of the fuci." I think that this is an over-calcula- 

 tion. The error may have arisen from the fact, that, by long 

 boiling, the cellular tissue of these plants is changed into what 

 possesses at least this property of mucilage, that it is precipi- 

 tated by dinacetate of lead. From bleached Fucus sahnatiis, I 

 have procured, by infusion, almost exactly half its weight of the 

 principle in question. Some of the sea- wares contain more of 

 this principle than others. 



To procure the mucilage in a pure unmixed condition, this 

 formula will be found adequate : — Bleach some of the Fucus 

 by exposure to the sun — bruise it — macerate a day or two in 

 often-changed, acidulated water. This dissolves out the sa- 

 line matters. Boil half an hour in an extremely attenuated 

 aqueous solution of sulphuric acid. The sulphuric acid, I 

 conceive, aids the disintegration of the tissue of the wares, and 

 thus promotes the escape of the principle in quest from its 

 cellular confines. Agitate the decoction with animal charcoal, 

 a little carbonate of baryta, and a little litharge. Filter and 

 evaporate over a water bath. After powdering the mass ob- 

 tained in this way and washing it with alcohol, in order to se- 

 parate adhering chlorides, &c., a pure mucilage is procured. 

 When long boiled with sulphuric acid this becomes similar to, 

 or rather identical with, gum arabic. 



Before proceeding to the practical application proposed to 

 be made of these facts, it may be well to recapitulate them. 



1^/, The common sea-wares contain great quantities of mu- 

 cilage. 2J, This mucilage is easily separable from the other 

 ingredients of the wares. Sd, A solution of mucilage does not 

 become stale or mouldy, ^th, By a very simple process it is 

 converted into gum arabic. 



Mucilage is one of the most nutritive of all vegetable proxi- 

 mate elements, as is suggested by its so general and abundant 

 distribution. The fuci we have seen to be plentifully supplied 

 with it. Many of these sea-plants luxuriate in unrestrained 

 and unused abundance in all the rocky parts of our rocky 

 coast. In some parts of that coast in the winter of every year, 

 and everywhere during that part of some years, might not the '^ 



