278 On the Employment of Sulphate of Copper, ^c. 



the effect is more remarkable. The action of alum (except as it re- 

 gards quantity) is much the same as that of sulphate of copper. In 

 the baker's phrase, it makes the bread sivell large. 



Sulphate of Zinc. — The results obtained from this salt are incon- 

 siderable, and the author is persuaded that if any supposed efficacy 

 has been attributed to it, it must have been confounded with sulphate 

 of copper. 



Sub-carbonate of Magnesia.^-No great effect on the rising of 

 bread. In the proportion of xi^^ it produces a yellowish color, which 

 may relieve the dark color of spoiled flour. 



Sub-carbonate of ammonia. — No very remarkable result. By 

 being changed to acetate it may perhaps, in common with the car- 

 bonates of potash and soda, preserve the moisture of bread for a 

 longer period. 



JMarine salt, — Like alum and sulphate of copper, it strengthens 

 the paste,' but with less power. It does not produce a bread so white 

 nor so well divided a crumb, as the other salts. Bread, however, is 

 much better for the use of it, for alum and copper give very httle 

 taste. Their crumb is more like that of a light cake than of com- 

 mon bread. 



A sufficient quantity of common salt may, like alum and copper, 

 serve as a substitute for leaven. 



Summary. — An experimental inquiry into the remarkable effects 

 of sulphate of copper in the process of panification, elicits the en- 

 couraging fact that the presence of this venomous substance can, in 

 the very smallest proportion, be detected by chemical analysis. 



Every consumer may apply the means of determining its existence 

 in bread, when in quantity too small to occasion any serious incon- 

 venience. A dvo"^ o( prussiate of potash ]et fallen the bread, in 

 a few seconds, gives a rose color, even when the sulphate is only 

 9 oVo psrt of the mass. 



These researches also prove that the sulphate of copper cannot be 

 introduced into bread, in very large quantity, not even in the propor- 

 tion of 3 5V0 P^^^tj without injuring its appearance, and arresting the 

 fermentation of the dough. A disagreeable odor also becomes man- 

 ifest as soon as the proportion of the sulphate exceeds ^oVo part of 

 the bread. 



The author expresses the hope that the numerous experiments, 

 detailed in his memoir, will throw some additional light on the subject 

 of panary fermentation — still too obscure to justify any attempt at 



