WHEAT. 178 



Schwertz made many experimonts in Wurtember^ to determine the 

 qnantity of flour yielded by spelter, and he found tliat from 100 cf grain 

 he obtained 90 of husked j^rain, and 8.7 of hran ; thiM-e was a U)ss of 

 1.3. The quality of tiie lloiir always varies according to the wheat 

 from which it is procured : it contains moisture in variable })roi or- 

 lions, gluten in variable proportions, and, finally, various quantities 

 of woody matter. The wheat of the south is harder :ind tougher than 

 that of the north, and appears richer in azotized principh^s ; as it con- 

 tains less moisture, it also keeps better ; it is, undoubtedly, in conse- 

 quence of the large quantity of water which our northern wheats 

 contain, that we meet with such indifferent success when we attempt 

 to keep them for any length of time in (uir granaries. The wheat of 

 Alsace, for example, frequently contains from 10 to 20 per <;ent. of 

 moisture ; a'nl 1 have ascertained, by various experiments, that it is 

 almost impossible to keep it without change, in vessels hermetically 

 sealed. To secure its keeping, the proportion of water must be re- 

 duced to from 8 to 10 per cent., and this is nearly the quantity of 

 moisture contained in the hard and horny wheat of warm countries. 

 I am therefore of opinion that we shall never succeed, in these coun- 

 tries, in keeping wheat for any length of time — in the magazines of 

 fortified towns, for example — whatever care be taken. 



The flour of the cereals, particularly that of wheat, absorbs a large 

 quantity of water, and forms a paste, which is by so much the firmer 

 and more elastic, as the flour contains a larger proportion of gluten : 

 the azotized principle of wheat has, in fact, the remarkable property 

 of being extensible like a membrane, when it is inoist,and this prop- 

 erty it communicates to the whole of the paste or dough. In order 

 to be brought into the state of doijgh fit for making bread, flour will 

 absorb from 55 to 70 per cent, of water. The quantity of bread ob- 

 tained necessarily depends upon the heat and length of exposure in 

 the oven; but, in a general way, from 100 of dour, 130 of the best 

 white bread of Paris is procured. In the country, the bread is 

 generally less baked than in Paris or London, and therefore retains 

 more water ; so that from 100 of flour, 140, 145, and 146 of bread are 

 made : thus, admitting 16 per cent, of moisture as existing in wheat 

 originally, we have of absolute dry matter 64}, 57, and 56 in different 

 kinds of bread. 



Bread is by so much the more nutritious as it is made from flour 

 containing a larger proportion of gluten ; to add any starch therefore 

 is to prejudice the interests of the consumer; nevertheless it is the 

 practice to do so almost openly ; when potato starch is at a low 

 price, the adulteration frequently begins with the miller and is ex- 

 tended under the baker. The quantity of gluten contained in differ- 

 ent kinds of wheat varies greatly. Vauquelin found in the — 



Flour of French wheat 



Flour Iroiu hard Odessa wheat 

 Flour froMi soft Odessa wheat 

 Flour from the baker's 



The method of analysis employed by Vauquelin, whose results 



15* 



