508 COMPOSITION OF BARLKY. 



the solution added to the water with which tlie dough is to be made, ia 

 the proportion of about one grain to two pounds of flour. It gives the 

 bread a fairer colour, and thus permits the use of inferior flour, and it causes 

 the bread to retain about six per cent, more water without appearing inoist- 

 er. Even in the small proportion of one grain of the sulpliate to G, or 

 7 lbs. of flour, it produces a very sensible effect (Kuhlman). 



Other adulterations also exercise a similar influence. Alum improves 

 the colour of the bread, raises it well, and causes it to keep water, but it 

 requires to be added in larger quantity than the more poisonous sulphate 

 of copper. Common salt likewise makes the paste stronger, and 

 causes it to retain more water, so that the addition of salt is a real gain 

 to the baker. 



From all these facts, therefore, we may infer that, independent of the 

 relative proportions of gluten, very slight differences in composition — 

 8uch as have not yet been sought for or appreciated — may materially 

 affect the relative weights of bread obtained by the baker from different 

 samples of wheaten flour. 



§ 13. Of the composition of barley, and the injiuence of different manures 

 upon the relative proportions of its several constituents. 



The grain of barley consists of nearly the same substances as that of 

 wheat, but in proportions somewhat different. These proportions, how- 

 ever, are aflfected both by the kind of manure with which the land is 

 dressed, and by the nature of the soil on which the seed is sown. 



1°. Manure. — The effect of manure appears from the following table, 

 containing the results of Hermbstadt, obtained in the same way as those 

 with wheat already described (p. 503) : — 



u . 6 J: u -2 . « P'S 



KIND OP S -^ 3 h A E rtp ■B'i'E ar^rS 



MANURE. ^ 3=£§5 3= = I -§ ^ O «^S 



Ox Blood 10-4 13-6 57 0-4 59-9 4-6 4-4 4 0-4 16 



Night-soil 10-2 13*6 5-8 0-5 59-6 4-5 4-3 0-5 0-6 13 



Sheep's dnng... 10-3 13-5 5-7 0-4 599 4-6 4-4 0-4 0-3 16 



Goat'sdung 10-4 13-5 57 0-4 599 46 4-5 0-4 0-3 15 



Human urine... 103 136 5-9 05 59-6 4-4 4-4 0-4 0-7 13i 



Horsedung 10-4 13-5 5-7 0-4 59-7 4-5 4-5 0-4 0-4 13 



Pigeon's duiig .. 10-4 13-5 5-6 0*4 598 46 45 0-4 0-4 10 



Cow'sdung 10-8 13*6 33 02 61-9 4'8 46 0-3 0-3 11 



Veget. manure.. 10-8 13-6 2-9 0-2 62-2 4-9 4-8 0-2 0-1 7 



No manure 10 8 13-6 2-9 01 625 5-0 47 0-1 0-1 4 



In so far as reliance is to be placed i^on the numbers in the above 

 table, as indicative of the general effect of the several manures men- 

 tioned, it would appear that the relative proportions of gluten, albumen, 

 and starch do not vary very much until we come to cow-dung, when the 

 former two substances sensibly diminish. Further experiments, how- 

 ever, are required upon this subject (see page 514). 



2°. Soil. — The effect of soil upon the barley crop is known to all 

 practical farmers — so that the terms barley-land and wheat-land are the 

 usual designations for light and heavy soils adapted especially to the 

 growth of these several crops. On clay lands the produce of barley is 

 greater, but it is of a coarser quality, and does not malt so well-^n 

 loams it is plump and full of meal — and on light chalk soils the crop is 

 ligtt, but the grain is thin in the skin, of a rich colour, and well adapted 



