272 Use of Sulphate of Copper, SfQ. in Bread. 



In these experiments, the entire freedom of the tests employed, 

 from copper, is very important. Water, distilled from a copper 

 alembic is rarely exempt from slight traces of the metal. 



In a great number of trials which the author has made, the quan- 

 tity of copper which he found was so small,- that he v/as obliged to 

 answer the question of any addition of sulphate to the materials of the 

 bread, in the negative. From several facts it is inferred that traces 

 of copper may naturally exist in flour, and consequendy in the grain 

 which produces it. This he considers to be true with respect both 

 to wheat and rye. There is nothing in this fact surprising to chem- 

 ists. M. Sarzeaud has detected this metal in several organic pro- 

 ducts, and M. Meissener, of Halle, has discovered it in a great num- 

 ber of plants. Still there is a wide difference between the quantity 

 thus introduced by nature, and the smallest portion fraudulently add- 

 ed by the baker. Bread which contains ^ain o of sulphate, gives 

 an ammoniacal liquor, which, when rendered slightly acid, becomes 

 immediately rose colored by ferro-prussiate of potash, while that 

 from wheat and flour requires a long time, and in many cases the 

 prussiate of copper becomes apparent only from its giving a color to 

 the white base, which appears to be a litde . earthy phosphate dis- 

 solved by the ammonia. 



On the employment of alum in baking, and the means of detecting it 



in bread. ■ 



The use of alum appears to be very ancient. It serves to dis- 

 guise the quality of bad flour, and even to enable the baker to add a 

 portion of the flour of beans or peas, and perhaps of potatoes, without 

 an easy detection. 



The quantity of alum, requisite to make a light porous bread out 

 of inferior flour, varies from yi^ to -^j^ of the flour employed, or 

 from yi^ to ToTT o^l^he bread obtained from it. It enables the ba- 

 ker also to dispense in whole or in part with the salts commonly 

 used. 



Its injurious action upon the health is not to be compared to that 

 of sulphate of copper, and yet taken daily into the stomach, it may 

 seriously affect the system. 



Dr. Ure's method of detection is after soaking the washings of 

 stale bread in distilled water, to press out the water, filter it, and test 

 it by muriate of barytes. This, says our author, will shew pip of 



