1 62 On the Agency of the Carbonate of Magnesia 



cumstances that led me to use this substance, and to bring for- 

 ward some facts that tend to elucidate the mode of its operation. 



On examining several samples of new wheat, it appeared to 

 roe the injury they had sustained arose principally from the grain 

 having germinated. In this process it is understood a part oi 

 the farinaceous matter of the grain is converted into sugar. 

 Tlie changes tlms.produced in the grain seem to be analogous to 

 those effected in starch by diluted sulphuric acid and heat : only 

 in the one case they result from chemical agencies alone ; i-i 

 the other, the chemical agencies are assisted bvthe living powers 

 of the infant plant. The production of saccharine matter in the 

 gvain is conceived to be accompanied by an incipient fermenta- 

 tion : this, though checked in the act of drying the corn, might, 

 in the subsequent operations to which the flour was exposed 

 when made ittto "dougli and leaked, induce the acetous fermen- 

 tation. Hence, I thought it not improbable that acid matter 

 might be developed in bread made from the new flour with the 

 usual additions. 



In order to try if the new flour was at all acid, I put samples 

 of the worst qTiality in distilled water; but after several hours 

 tiie fluid did not affect litmus paper, or the still more delicate 

 test of an infusion of red cabbage. I likewise exposed fer- 

 mented dough made from the same flour (with the additions of 

 yeast, salt, and warm water,) to an infusion of cabbage ; but no 

 change of colour could be perceived in it. But after some of 

 tlie dough had been baked, the bread was clammy, had a sin- 

 gular smell, a sourish taste, and left on the palate a sense of 

 bitrerness. When some of this bread was put in distilled water 

 and suffered to remain for about a day, the fluid produced a 

 slight tint of red in an infusion of cabbage; and after three days it 

 had a slight acid taste, and perceptibly reddened litmus paper. 

 On making a comparative trial with bread made from good old 

 flour, under simi'ar circumstances, I could not by the most de- 

 licate tests detect the presence of any acid. Hence it seemed 

 acid matter was formed in the baking of the new flour, and the 

 bread had a tendency to acidity. I found likewise, in cases 

 when a few drops of vinegar, or any of the mineral acids diluted, 

 were put into dough made from good old flour, the bread wm 

 disposed to be clammy, and had a taste similar to that of bread 

 made from bad i ew flour. These circumstances led me to ima- 

 gine that the bad qualities of bread made from the new flour 

 were connected with the appearance of acid matter during the 

 baking : and the application of alkaline substances, as cor- 

 rectives, immediately became, obvious. After repeated trials, f 

 found that the fixed and volatile alkalies, their subcarbonates 

 and carbonates, improved the new flour toa certaio extent; and 



J wa« 



