ON THE FECULA OF 6UEEtt PLANTS. J7 



Parlous and ihfoluble in water; it mutt be acknowledged that • 

 there is no other product in vegetables to which it approaches 

 fo nearly. But we fhall find, that, in order to give it this cha- 

 racter more perfectly, it is only neceffary to add to it a little 

 oxigen. 



The oxigenated muriatic acid, in a few days, bleaches and But rendered 

 . , , „ . . . ... , .. , more completely 



hardens the green retm ; it then becomes ropy, like boiled re f inous b y ox- 



turpentine and its colour is very diffufible in water; but if the igcnatioa. 

 green part of the fecula belonged to the coloured juices, con- 

 tained in dying ingredients, oxigen would not convert it into 

 a refin. At prefent, when experience has taught us not to 

 fix fuch ftrict limits to vegetable produces as heretofore, be- 

 caufe we fo often find them united by intermediate qualities, 

 we (hall not be furprifed to fee that a refin, at its maximum of 

 divifibility, can mix with water. Do we not find that cam- 

 phor, effential oils, both animal and vegetable, farcocolle, &c. 

 are completely diflblved by water ? Yet we do not from that 

 circumftance exclude fuch products from the claffification 

 which analyfis affigns to them. 



The green fecula acquire, by the action of oxigenated mil- When it turn* 

 riatic acid, that tawny brown colour which indicates the de- 

 cay of the leaves in winter, and their aqueous difTufion be- 

 comes abundantly turbid. On the whole, then, we may infer, 

 that though the colouring matter of the fecula cannot relift the 

 action of water, when extracted by alcohol, it is neverthelefs, 

 in all its other qualities, a fubftance truly refinous; and though 

 this product, which is one of the moft curious of the vegetable 

 kingdom, becaufe it adorns it by its various combinations, has 

 not been admitted in the fyftem of chemical knowledge, yet the 

 chemifts who have been the moft occupied with it, fuch as 

 Rouelle, Danel, Sage, Parmentier, &c. have not thought it 

 lefs worthy of their inveftigations. 



This refin, when diffolved in potafli, quits it to unite with This refin quiti 

 filk, which it tinges of a clear green, but too fugitive to be- JJ^SJSr, 

 come ufeful ; notwithftanding which it refills the action of with annrfcl 

 verjuice ; but its attraction for gluten in preference to the ve- ™ attcr llkc * 

 getable fibre, is conformable to eftabliflied principles; for, in 

 general, colouring bodies attach themfelves to animalifed fub- 

 ftances, rather than to the fibres of flax, hemp, or cotton. 

 There is then fomething in the fecula analogous to wool, to 

 filk, &c. It is the gluten. 



Vol. V.— May. C V. Let 



