56 Starcb. [BookVIIf. 



oil. Its coal is very difficultly incinerated, aud does 

 not afford fixed alkali. 



From thefe facts it follows, that this fubftance is to- 

 tally different from all the others known to exift in 

 vegetables, and in many of its characters refembles the 

 fibrous part of the blood. It is to this gluten that 

 wheat- flour owes its property of forming a very adhe- 

 five pafte with water. This gluten does not appear to 

 exift in any confiderable quantity in other farinaceous 

 fubftances, as rye, barley, buck-wheat, rice, &c. M. 

 Berthollet thinks t..ac this glutinous fubftance contains 

 phofphoric fait, like animal matters, and that this is 

 the reafon of the difficulty with which it is incinerated. 

 Rouelle the younger found a glutinous fubftance in 

 the fecula of plants, analogous to that of wheat. 



The powder which I remarked, as being feparated 

 from the farina, and which, being only fufpended 

 and not diffolved in the water, falls to the bottom by 

 reft, is the amylaceous fecula or ftarch, which indeed 

 compofes the greater part of the flour. This fub- 

 ftance is very fine and foft to the touch ; its tafte is 

 fcarcely fenfible. When firft extracted by the procefs 

 which has been defcribed, irs colour is greyiih ; but the 

 ftarch-makers render it extremely white, by fuffering it 

 to remain in the water for a time, after it has become acid. 

 Starch feems nearly allied to mucilaginous matters, 

 and is totally different from the glutinous fubftance laft 

 defcribed. Its habitudes and products with the fire, or 

 with nitrous acid, are nearly the fame as thofe of gurn 

 and of fugar; but k differs from thefe fubftances in 

 being fcarcely, if at all, acte J on by cold water, though 

 with hot water it forms a gelatinous fluid, It feems to 

 be more remote from the faline ftate than gum, as 

 gum is mere remote from it than fugar. Starch burns 

 without emitting an empyreumatic frnell. By diftil- 



lation 



