Nutritive Value of Prickly Comfreij. 
387 
bewilder rather than to enlighten him, I would mention, for the 
guidance of intending purchasers of potash-salts, that the main 
point for their consideration is to make sure of obtaining in these 
salts as much potash as possible for a given price. During the 
past season I have made a good many analyses of native and 
calcined kainite, and of various kinds of Stassfurt potash-salts, 
and have found the percentage of potash in the several salts to vary 
considerably. I would, therefore, advise the buyer of German 
potash-salts to obtain in writing, from the dealer or importer, a 
guarantee, stipulating the percentage of potash which the native 
or calcined kainite, or any other species of crude or impure 
potash-salts, is to contain. When the bulk is delivered, the pur- 
chaser should take a fair average sample and have it tested for 
potash ; and, if the analysis shows less potash than the guaranteed 
percentage, to make a deduction from the price corresponding with 
the value of the deficient potash. 
Laboratory, 11, Salisbury Square, Fleet Street, E.G., 
July, 1871. 
XV. — On the Composition and Nutritive Value of the Prickly 
Comfrey {^Symphytum asperrimum). By Dr. AUGUSTUS 
VOELCKEE, F.R.S. 
The prickly comfrey {Symphytum asperrimimi) is a native of 
the Caucasus, whence it was introduced into England, in 1811, 
as an ornamental plant, by Messrs. Loddige, of Hackney. It is 
perfectly hardy in Great Britain, a rapid grower, and in mode- 
rately good soils reaches a great size ; and even in poor soils 
grows over 2 feet high. It is a perennial plant, with fine 
reddish-blue flowers, and as it may be cut down three or four 
times in one season, it produces an abundance of succulent green 
food, which is said to be particularly useful for dairy-cows. 
It is conveniently propagated by divisions of the root ; the 
root may be cut into small pieces, as the smallest bit will 
produce a plant. The best time for planting the root-cuttings 
is February or the beginning of March ; on good soils it should 
be planted in rows 2 to 2^ feet apart, and 15 to 18 inches apart 
in the rows. If the plantation is made early in the year and the 
cuttings strike root and get well established before genial spring 
weather sets in, it will yield two good cuttings the first season ; 
and in the succeeding years, if it is kept fairly clean and occa- 
sionally manured, it will give three or four cuttings furnishing 
an abundance of green food from April to October. 
The prickly comfrey, although first introduced into England, 
