122 
RHEUM PALMATUM. 
dry, exposed to a free current of air, but shaded from the sun ; in 
^bout three months they are sufficiently dry for packing*. ^^Unmr 
j,^. Various species of rhubarb have been long cultivated in this 
country; in 1629, Mr. Parkinson first cultivated the Rheum 
Raphonticum ; and the Rheum Undulatura was shortly afterwards 
introduced : in 1762, the seeds of the Rheum Palmatum were 
procured from Russia, and the plant was cultivated at Cambridge 
and Edinburgh ; and since that lime, this species and the Rheum 
Undulatum,have been extensively propagated by gardeners, both for 
medicinal and culinary purposes ; the Rheum Undulatum is most 
generally preferred and used for the latter purpose. The cultivation 
of this plant is by no means difficult; the seeds are sown in spring, 
in a light soil, and next spring the plants are transplanted out at th^ 
distance of three feet from each other ; during the summer season 
4he ground must be frequently hoed, to keep it clear from weeds, 
^jaind that the soil may be kept loose about the plant ; before winter, 
|he earth should be thrown up round the plant, by which means 
t ^lje root is preserved from the action of the cold atmosphere ; the 
,,jaiird year the plants begin to flower, but the root will be strengthened 
by nipping oS the buds as they appear, and not allowing them to 
proceed to fructification; at the end of six or seven years, the roots 
may be taken Up for use. The process directed for preparing them 
for the market is as follows:— they are first to be washed in a large 
quantity of water, and the fibres and small roots cut off ; they are 
to be well brushed in fresh water, and cut into pieces of a 
proper size ; the brown bark being rasped off, they are a,gain 
thrown into freshwater for three or four hours, when they throw 
out a great quantity of gummy matter; they are then taken out, 
allowed to drip for some hours, during which they exude a 
white transparent gummy matter, resembling jelly. This process 
being over, they are put into a stove, heated to 120« or 130% till 
dry; when perfectly dry, the wrinkles must be rasped out, and 
the pieces thus dressed are put into a barrel, and rolled about for the 
space of half an hour, when they get covered with a fine powder, 
formed by their attrition. Baum6 says that rhubarb, prepared in 
this way, has not only the appearance of foreign rhubarb, but that 
it could be immediately powdered ; four ounces of French rhubarb 
yielded to him 1644 grains of extract ; and the same quantity of 
foreign rhubarb, 1600 grains. We do not, however, mean to pro- 
pound this as the best mode of preparation, as it may require some 
further experience before this is ascertained. The chief peculiarity 
in the foregoing process of Baume, is the steeping the roots in water 
