071 the Fecida of Green Plants. 155 



he gave On green feculae, and of which no mention is made 

 in The System of Chemical Knowledge ; no doubt because, 

 according to the ideas of this illustrious author, Rouelle had 

 confounded albumen with gluten, and the detail of his mis- 

 take must have appeared to him a matter of indifiereiice to 

 the histor)' of chemistry-. 



Rouelle, however, found in the fecula of sorrel a pro- 

 duct so strongly possessed of the chemical properties of al- 

 bumen, that he particularly insisted on it, to call the atten- 

 tion of chemists to a substance so animalizcd; and as he af- 

 terwards extracied it from a plant which, according to Four- 

 croy, -does not fm-nish the slightest vestige of albumen, it 

 is now certain, as it was then, that Rouelle was the first 

 who found in green juices and feculas a product which, if 

 it ought not to be distingviished by the name of alhume'n, 

 has, however, all its properties in such a degi-ee that it must 

 appear no less proper to make a figure in the history of their 

 discoveries than albumen itself. 



It is to the same penetration tliat we are indebted for 

 t"hose astonishing relations exhibited by caseum and o-luten^ 

 when they have both experienced a kind of fermentation 

 which transforms them into that cellular, odorous, and sa- 

 voxiry combination called cheese: and in this singular re- 

 sult gluten approaches nearer to its model the more care- 

 fully it has been washed. Macquer, by asserting, as is now 

 every vvhere repeated, that it is indebted for a part of these 

 changes to a residuum of starch, had not correct ideas. 

 Starch, a substance always inert in fermentation, in that of 

 bread, and of beer, and 'even in germination, would only 

 serve to retard that experienced by gluten itself, and cou- 

 Pequently could obliterate only in 'part the traces by which 

 Rouelle discovered the resemblance of these two products. 



And even their analysis passes beyond the limits which 

 had been assigned to them ; for, when gluten has changed 

 its insipid and viscous mucosity for the caseous statCj when 

 it has passed through all the periods of that fermentation 

 peculiar to it to arrive at this state, it is found seasoned 

 with those acrid and burning salts which form the principal 

 merit of the cheese of Roquefort,* salts which have no affi- 

 nity with that which is added, and which are found equally 

 *trong in the curd that has been v.ashed and left to its own 

 fermentation. 



In the cheese of gluten, indeed, as in that of animals^ 

 potash and sulphuric acid will detect that ammonia and vi- 

 negar which Vauquclin discovered. I3 the ammoniacal 

 acetate, then, one of the ingredients which seasgn cheese? 



.1 know 



