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horse-radish, and seacale. No matter where you set them to grow they 
invariably separate large quantities of sulphur and nitrogen, as may be 
painfully demonstrated when the plants are decaying, or when the cook is 
emptying the saucepan in which cabbages have been boiled. !S T one are 
poisonous and nearly all are in some way or other used as adjuncts to our 
food, and possess strongly marked antiscorbutic and stimulating qualities. 
The order derives its name from the peculiar and constant cruciform 
type so conspicuous on the flowers. They invariably have a quaternate 
arrangement. The Corolla has four petals and the Calyx four sepals. 
Although the stamens are six in number yet only four are long. One of the 
most useful of the Cress worts is the mustard plant, the seeds of which 
when powdered form (or ought to form) our table mustard. 
No article of food however is more adulterated, and seldom can this 
condiment be met with at the dinner-table with even a moderately 
pungent taste. At an examination before the parliamentary committee some 
of the witnesses plainly admitted that the adulterants used were wheat- 
flour, turmeric, capsicum, ginger, pepper, potato-starch, plaster of Paris, 
charlock, pea-flour, radish and rape seeds, linseed meal and yellow ochre. 
In short, if the microscopist wants a little experience he cannot do better 
than get a few samples of so-called mustard, such as those on the table and 
purchased at some of our Bristol shops. Many of these when burnt give 
from 30 to 50 per cent, of ash while the genuine seeds only yield about 5 per 
cent. In manufacturing our common flour of mustard the seeds of the black 
and white mustard are crushed and powdered in mortars and sifted. Four 
qualities are supplied to the trade, viz.: seconds, fine, superfine, and 
double superfine ; the last is the purest though seldom kept by the grocer. 
The black seeds are the principal ones used in the manufacture, but for 
reasons presently to be stated the white ones are advantageously added. 
Our housekeeper when mixing the table-mustard little imagines what 
interesting chemical reactions are taking place in the cup, by which the 
pungent taste so much admired is developed. For strangely enough the 
essentia] oil does not pre-exist in the seeds at all, nor have the seeds the 
slightest warmth before the addition of water. 
Before entering upon and describing what takes place when the mustard 
pot is filled, it will be better to describe the two species of mustard plants 
which furnish the seeds in. question. The first and most important is the 
Sinapis nigra (Linn.) or black mustard. The plant occurs frequently in 
the neighbourhood of Bristol in waste places and on the banks of hedges. 
In some botanical works it is described under Boissier's genuine name 
