PURIFICATION OF THE JUICE OF THE BEET ROOT. 293 
salts of silver, binoxide of mercury, &. With the latter compound 
the solution even assumes the natural tint that takes place in sugar 
after long exposure to the air. 
These facts established, it becomes evident that, in order to simpli- 
fy the production of beet-root sugar, the following reagents must be 
sought for. 
First, a substance of slight solubility, capable of coagulating all 
albuminous matters; free from deleterious action on the sugar; 
innocuous in itself; easily withdrawn from the syrup, in case a small 
quantity should remain in solution ; and finally, of low price. 
Secondly, an additional substance possessing a certain oxidizable 
power, capable of either destroying at once the coloring matter, or of 
transforming this into the brown compound, and afterwards absorbing 
it; and possessing also the innocuous qualities, absorbing action, 
and low price of the preceding substance, together with the capability 
of being indefinitely reproduced. 
Sulphate of lime, either in the natural state or in that of Plaster 
of Paris, fulfils the first conditions more perfectly than any other 
substance that I have experimented with. It is neutral (a condition 
that I regard as essential) —is without action on the sugar, very slightly 
soluble, innocuous, cheap, and possessed of remarkable coagulating 
powers with regard to the albuminous matters of vegetable juices 
generally, and of those of beet-root in particular. A very small 
quantity, indeed, is sufficient to produce this effect. The process of 
purification can thus be carried on to great advantage: the scum is 
thick and easily collected, and the juice is readily drawn off in a proper 
state of limpidity. 
This reagent, however, which completely removes all coagulable 
substances, does not touch the colouring matter. The juice conse- 
quently, after the separation of the scum, quickly assumes a dark tint. 
Animal-black is almost without action upon this ; it only removes the 
oxidized matters, so that the partially-decolorized juice soon regains 
its former hue. An oxidizing body is therefore required, in order 
to effect at once that which the air produces only after long ex- 
posure. 
Amongst the numerous bodies which I have examined under this 
point of view, and which I need not enumerate here, the hydrated 
Sesqui-oxide of iron affords the best results. If, for example, after 
