84 SCIENCE PRIMERS. [MATERIAL 



of water and well kneaded with the hands, it will 

 become pasty, while the water will become white. If 

 this water is poured away into another vessel, and the 

 kneading process continued with some fresh water, the 

 same thing will happen. But if the operation is re- 

 peated the paste will become more and more sticky, 

 while the water will be rendered less and less white, 

 and at last will remain colourless. The sticky 

 substance which is thus obtained by itself is called 

 gluten ; in commerce it is the substance known as 

 maccaroni. 



If the water . in which the flour has thus been 

 washed is allowed to stand for a few hours, a white 

 sediment will be found at the bottom of the vessel, 

 while the fluid above will be clear and may be poured 

 off. This white sediment consists of minute grains of 

 starch, each of which, examined with the microscope, 

 will be found to have a concentrically laminated 

 structure. If the fluid from which the starch was 

 deposited is now boiled it will become turbid, just as 

 white of egg diluted with water does when it is boiled, 

 and eventually a whitish lumpy substance will collect 

 at the bottom of the vessel. This substance is called 

 vegetable albumin. 



Besides the albumin, the gluten, and the starch, 

 other substances about which this rough method of 

 analysis gives us no information, are contained in the 

 wheat grain. For example, there is woody matter or 

 cellulose, and a certain quantity of sugar and fat. 

 It would be possible to obtain a substance similar to 

 albumin, starch, saccharine and fatty matters, and 

 cellulose, by treating the stem, leaves, and root in a 

 similar fashion, but the cellulose would be in far 



