62 



AMERICAN WHEAT AND CORN. 



sary to add on the average about 56 per cent, of water, or water and milk. 

 The result has been that we have obtained a much larger yield of bread 

 per hundred pounds. 



The effects of variation in physical conditions are illustrated by the 

 following data : 



Variation in yield dependent on percentage of water used (other conditions being the same), 

 oil size of loaves, on difference of temperature, and on time of baking. 



[Ohio patent flour.] 



In all these cases the yield is largely modified by the change in a 

 single condition, the remaining ones being constant. It is evident, 

 therefore, how complicated a comparative series of experiments becomes 

 when all the above conditions exercise their modifiying effects and 

 must therefore be kept constant. 



There are also conditions of mixing and raising which in a like man- 

 ner affect the yield. As every one knows, there are different methods 

 of carrying out these operations, and larger or smaller amounts of yeast 

 may be used. The method which we have finally employed is a modi- 

 fication of the Vienna procedure as described by Horsford. The dough 

 is mixed in mass with press yeast and allowed to rise till the outer pel- 

 licle is just cracking. It is then rekneaded into loaves, put in pans, and 

 set in a warm place until the dough is again risen, when it is baked. 



The baking was carried on in a large gas-stove, the oven of which by 

 means of a thermometer could be kept at a very regular temperature. 

 All the materials used and the products obtained were weighed to 1 

 gramme (15 grains), so that the results as far as manipulation go may 

 be regarded as> accurate. 



Having fixed these conditions, as they appear in the table which fol- 

 lows, the experiments were conducted with the different flours which 

 have been collected. 



