RELAX VE WEIGHTS OF FLOUR AND BRAN. 499 



depends considerably upon the hardness of the grain. From such as is 

 soft it peels off in flakes under the stones, whereas, when the grain and 

 nusk are flinty, much of the latter is crushed and ground — adding to the 

 weight of the flour, but giving it a darker colour, and lowering its quality. 



The country millers generally separate their wheaten flour by sifting 

 into four parts only — fine flour, boxings, sharps or pollard, and bran. 

 In London and Paris no less than six or seven qualities are manufac- 

 tured and sold by the millers.* The value of the wheat to the miller 

 depends very much upon the quantity of fine flour it will yield, though 

 he cannot always judge accurately of this point by simple inspection. 



The experimental wheats of Mr. Burnet, of Gadgirlli,f raised all from 

 the same seed differently manured, gave respectively 54|, 63^, 65|, 

 66i, 68y, and 76i lbs. of fine flour from 100 of wheat, so that the kind 

 of manure applied to the land appears materially to affect the relative 

 proportions of flour and bran. 



Again, Colonel le Couteur's samples of wheat (p. 489) of different va- 

 rieties, grown under the same circumstances, gave from one field 80| 

 and 79| lbs., and from another 72^ and 78^ lbs. from 100 of wheat — so 

 that wpon the variety of seed sown also, though in a less degree, the quan- 

 tity of fine flour is dependent. 



§ 8. Of the composition of wheaten flour. 



1°. Water. — When wheat is kept for ayear it loses a little water, be- 

 coming one or two pounds a bushel heavier than before. When put into 

 the mill and ground it becomes very hot, and gives off so much watery 

 vapour, that the flour and bran, though together nearly twice as bulky, 

 are nearly 3 per cent, lighter tlian tlie grain before it was ground. A 

 further loss of weight is said lo take place when the flour is kept long in 

 the sack. If fine flour be slowly heated to a temperature not higher 

 than 220 for several hours, it loses a quantity of water, which, in up- 

 wards of 20 samples of English flour which I have examined, has varied 

 from 15 to 17 per cent, of the whole weight. It may, therefore, be as- 

 sumed, that English flour contains nearly a sixth part of its weight of 

 water — or every six pounds of fine flour contain nearly one pound of 

 water. 



2°. Gluten, albumen, caseine, starch, gum, and sugar. — When the 

 flour of wheat is made into dough, and is then washed carefully with 

 successive portions of water upon a fine gauze or hair sieve, as long as 

 the liquid passes through milky, the flour is separated into two portions — 

 the starch, which subsides from the water, and the gluten, which remains 

 in the sieve (p. 116). If the water be poured off', after the starch has 

 subsided, and be heated nearly to boiling, it becomes troubled, and flakes 

 of vegetable albumen (p. 117) are seen to float in it. On setting aside to 



• These are called respectively in London and Paris— 



London. Paris. Called. 



Fine flour. White flours, 1st quality, de ble. 



Seconds. do. 2d do. de le gruau. 



Fine middling^s. do. 3d do. de 2e gruau. 



Coarse middlings. Brown meals, 4th do, de 3e gruau. 



Pollard. do. 5th /lo. de 4e gruau. 



Twentypenny. Bran, fine and coarse. 



Bran Waste, &c., Remoulage and Recoupe. 



. Page 362, and Appendix, pp. 54 and 70. 



