JO Memoir on Gluten. 



vifcid, and had a great refemblance to grayifh white glue. 

 In this ftate I employed it for making the following trials : 



I triturated four grammes of this glue in a glafs mortar, 

 after having poured over it fome drops of alcohol. The 

 gluten appeared to me to diflblve. I gradually added al- 

 cohol, and thus brought the gluten to the liquid confidence 

 of thick fyrup. I incrcafed the quantity of alcohol, hoping 

 to obtain a complete folution ; but when the quantity of al- 

 cohol was nearly double that of the gluten, the latter fuddenly 

 foparated, reappeared under its firft form, and it was impof- 

 fible for me to charge the folution more. I filtered the al- 

 cohol, which patted with a flight amber colour. 



To afcertain whether this folution contained much gluten, 

 I poured over it an equal volume of diftilled water : the mix- 

 ture immediately became white like an emulfion, and fuf- 

 fered to be (lowly depofited an abundant precipitate, which 

 had the appearance of a fecula, but which, when more clofely 

 examined, appeared to be gluten very much divided. The al- 

 coholic folution of gluten, when left for fifteen months in a 

 flafk {topped with cork, depofited a part of the gluten in the 

 form or a white, thick, elaftic membrane, which fhrinked 

 when expofed to heat, burned in the manner of animal mat- 

 ters, and had a great refemblance to white caout-chouc 

 formed from the juice of the heraea. 



I evaporated, at a gentle heat, the remainder of the folu- 

 tion, and obtained dry gluten, brittle, yellowifh at the fur- 

 face, and mining like beautiful varnifh. 



It refults from thefe experiments, that the gluten which 

 has experienced acid fermentation is in a great part foluble 

 in alcohol. This effect is owing, no doubt, to the acetous 

 acid which is formed by the fermentation, and which breaks 

 the force of the aggregation of the gluten ; for I kneaded the 

 frefh gluten a long time in alcohol without being able to 

 diflblve a fenfible quantity. This chemical fact is of very 

 little importance in itfelf, but it fuggeits fome ufeful applica- 

 tions. 



Having brought the fermented gluten to the confidence of 

 fyrup by means of alcohol, I fpread this thick folution with 

 a brufh over different bodies, fuch as wood, glafs, and paper. 

 It dried fpeedily, and formed a tranfparent varnifh, which 

 adhered ftrongly and did not become fcaly. Paper varnifhed 

 in this manner might be fubftituted for that brought from 

 Lngland under the name of papier a cautcre* . 



The fermented gluten, diluted in acetous acid, furnifhed a 



•.We imagine the author means that kind of brown paper in which 

 >ron ; .!''[ed up. — Edit. 



varnifh 



