100 MR. SCHUNCK ON RUBIAN AND ITS PRODUCTS OF DECOMPOSITION. 
common salt or sal-ammoniac, the substance separating in dark reddish-brown flocks, 
with a clear yellowish liquid floating above them. That erythrozym is not an un- 
combined substance, but a compound of an organic substance with lime, is proved by 
its behaviour towards acids. If it be treated with any acid, even acetic acid its 
colour changes from reddish-brown to yellowish-brown, and the filtered liquid is 
found to contain a considerable quantity of lime. The yellowish-brown flocks left 
on the filter, after all the excess of acid has been removed, do not again form wit ^ 
water a mucilaginous liquid like the original substance; and even an addition m 
lime water, though it restores the original chocolate colour, does not reproduce t at 
peculiar condition of suspensibility in water characteristic of it in its original state. 
The brown substance into which erythrozym is changed by the action of acids is 
soluble in caustic alkalies, forming pale purple turbid liquids. The ammomacal 
solution gives reddish-brown flocculent precipitates with most earthy and metalhc 
salts. When the solution in caustic soda is boiled, a disengagement of ammonia 
takes place. If erythrozym be treated with boiling nitric acid, it is dissolved and 
decomposed with a disengagement of nitrous acid. A small quantity of a white 
flocculent substance remains behind. Concentrated sulphuric acid chars it on 
heating. , , 
If erythrozym be mixed with water, and the mixture be allowed to stand tor a 
length of time in a warm place, signs of a more active process of fermentation begin 
to show themselves, especially in summer weather ; bubbles of gas are given oflF, and 
a peculiar smell is emitted, which, though disagreeable, cannot exactly be called 
putrid. During this process, which is evidently one of putrefaction in the stricter 
sense, the erythrozym loses its sliminess, and is converted into a red flocculent mass, 
which may easily be separated by filtration from the liquid. The ktter is clear, 
colourless and quite neutral. After erythrozym has passed through this second stap 
of decomposition, its power of decomposing rubian is found to have lost much of its 
intensity. It is during the first period of its decomposition, when no apparent change 
is taking place, that this power is most energetically exerted. During the second, 
or more strictly putrefactive stage, it acquires, however, the property of decomposing 
sugar. If erythrozym be mixed with a solution of cane sugar, and the mixture be 
allowed to stand for a considerable time until gas begins to be disengaged, the solu- 
tion acquires by degrees a decided acid reaction. What the acid is which is thereby 
formed, I have not yet ascertained. 
The erythrozym which I submitted to analysis, was prepared by precipitating it 
from an extract of madder with tepid water, by means of alcohol, collecting it on a 
filter, then treating it repeatedly with boiling alcohol until all matter soluble theiein 
was removed, and then washing it on a filter with cold water until the percoladng 
liquid no longer gave a precipitate with sugar of lead, after wdiich it was rapidly 
dried in the water-bath. It follows from the analyses which I have made, that the 
amount of lime which it contains is tolerably constant, and that it must consequently 
be considered as a definite compound of an organic substance with lime. 
