: ee ; 
272 Use of Sulphate of Copper, §c. 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 was 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 consequently in the grain 
which produces it. ‘This he considers to be true withrespect both 
to wheat and rye. There is nothing in this fact surprising to chem- 
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 ;;1,, of sulphate, gives 
an ammoniaca] 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 little earthy phosphate dis- 
solved by the ammonia. ; 3 : 
On the employment of alum in baking, and the means of detecting 
ae in bread. he Se 
. ‘ ; ina . 
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. — Soe 
The quantity of alum, requisite to make a light porous bread out 
-of inferior flour, varies from +3, to >, of the flour employed, or 
2 
from ;45 to 154-7 of the bread dbtained fom it. It enables the ba- 
= 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 my 
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 53% 
