in improving Bread made from the new FIo2ir. TG5 



property, it mav improve the texture of the bread, in a manner 

 somewhat analoaous to the improvement of stiff clav soils by 

 the mechanical agency of sand or gravel. 



Bread made from the new flour with the addition of carbonate 

 of magnesia is much lighter and more porous than w hen made 

 without it. I have at different tiaies made loaves with and with- 

 out the magnesia, using equal weights of the materials, and I 

 have always found the magnesian loaves of much larger size. 

 And I may further add (cceleris paribus), not only is the relative 

 bulk of the bread increased by the use of magnesia ; its actual 

 weight is likewise greater. Magnesia appears to give to the 

 new flour a greater capacity for water. For example : seventeen 

 ounces of new seconds, containing forty grains of magnesia, re- 

 quired eleven ounces of water at the temperature of 80' Fahr. to 

 make it into dough ; but ten ounces at the same heat were suf- 

 ficient for sixteen ounces of the flour. There was also a pro- 

 portional increase in the weight of the bread. The loaf with 

 magnesia (after making the necessary allowance;-) weighed 2G0 

 grains more than the one without it. Carbonate of magnesia, 

 by giving bread the power of fixing an additional quantity of vo- 

 latile materials, seems to act not unlike chalks or marles, when 

 applied on a sandstone or gravelly soil ; they increase its power 

 of absorbing and retaining moisture. 



The facts I have stated must, I should tl'.ink, tend to obviate 

 any objection against the use of small quantities of magnesia in 

 bread, from the fear of its accumulation in the system, on ac- 

 count of its supposed insolubility. As cold water readily dissolves 

 the new magnesian salt formed in the bread, the fluids of the 

 stomach, it mav l)e presumed, will be much more effectual sol- 

 vents of that substance. 



There is one circumstance that deserves mention, and with 

 the notice of which I shall close the present coinmunication. I 

 think I have ascertained the existence of the prussic acid in bread 

 made from the new flour*. Mv opinion rests on the fact, that 

 in the preceding experiments, when the strong sulphuric acid 

 was added to infusions of the bread evaporated to dryness, or 

 nearly so, the peculiar peach-blossom odour of t!ie prussic acid 

 became more or less perceptible on a gentle application of heat, 

 , I do not conceive the appearance of this acid can be referred to 

 any changes effected in the vegetable matter by the agency of 

 the suljjhuric acid, as the prussic odour was clearly perceived in 

 cases when the sulphuric acid was in a very diluted state. 



' rroin an cxi)crinici)t I made with bread made from jjood old flour, I 

 am iiicliiK'd to IilIIcvc it also roiit-.iiiu d t!i(; prussic acid, but ia mucli 

 smaller (inuntiiy tluiii the bread I'm-n npw (luur. 



L ;j Should 



