REPORT OF THE CHEMIST. 



115 



much as 15 pounds. The conditions upon which this variation depends 

 are largely physical, and include— 



Percentage of water used in the dough. 



Size of the loaves. 



Temperature of the oven. 



Time of baking. 



Of course in any series of comparative experiments these conditions 

 mast be closely observed and regulated. In order to learn the best 

 modifications for our work, a preliminary series was undertaken with a 

 flour from Ohio. 



In the beginning it was found that a dough made with any of our 

 Honrs and as small a percentage of water as was used by the McDou- 

 galls would be altogether too stiff for successful results. 



In the English experiments with flours from American wheat 46.4 per 

 cent, of water was used, but in our experience it has been found neces- 

 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), 

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



[Ohio patent flour.] 



Dependent on percent- 

 age of water used 

 (other conditions be- 

 ing the same). 



Dependent on size of 

 loaves. 



Dependent on difference 

 of temperature. 



Dependent on time of 

 baking. 



Percent, of 

 water. 



Yield of 

 bread. 



No. of loaves. 



Yield of 

 bread. 



Temperature. 



Yield of 

 bread. 



Minutes. 



Yield of 

 bread. 



54.5 



58.4 



62.1 

 62 1 



184.5 



136.9 

 144.9 

 145.5 



1 loaf. 

 10 rolls. 



138.6 

 129.6 







249 

 230 



136.9 

 140.8 



50 

 30 



134.6 

 140.2 



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 modifying 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 rekueaded 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. 



