NITROGENOUS BODIES. GLUTEN. ETC. 47 



SECTION V. OF ORGANIC BODIES CONTAINING CARSON, 

 HYDROGEN, OXYGEN AND NITROGEN. 



Although the substances containing the three first 

 named gases only, make up more than nine-tenths of 

 most plants, yet there is a class which in addition to 

 them contains nitrogen. This class, though so small 

 in proportion, is, as will be seen ultimately, one of 

 remarkable importance. 



The most easily obtained of these nitrogenous bo- 

 dies, is the one already mentioned as left behind when 

 the dough of wheaten flour is washed upon a cloth, to 

 obtain the starch, a. It is sticky, tenacious, and 

 somewhat like glue in its character : its name gluten 

 has reference to these properties, b. When heated, it 

 swells up to a great bulk, becoming quite full of holes. 

 For this reason flour which has much gluten in it is 

 called by the bakers strong, because light porous bread 

 can be easily made from it, and because it absorbs and 

 retains much water, c. The proportion of gluten in 

 wheat is from ten to twenty per cent. The wheat of 

 warm countries is said to contain more than that grown 

 in temperate latitudes. 



Several other grains contain gluten, but none so 

 much as wheat; they all, however, have bodies of the 

 same class, not generally resembling gluten in ap- 

 pearance and properties, but all containing nitrogen. 

 To these different names have been given : the nitro- 

 genous substance in peas and beans is called legumin; 

 that in indian corn, zein. In some other plants there 

 are substances of the same kind, called vegetable albu- 

 men, casein, etc. These are all somewhat similar in 

 their properties and composition. There is a little 

 sulphur and phosphorus in gluten, and in these nitro- 

 genous bodies generally, beside the four gases already 

 mentioned. 



