tted hydrogen. This agent will render the oil of a dark brown or
black colour, if any metal, deleterious to health, be present. The
practice of keeping this oil in pewter or leaden cisterns, as is often
the case, is objectionable; because the oil acts upon the metal. The
dealers in this commodity assert, that it prevents the oil from becoming
rancid: and hence some retailers often suffer a pewter measure to remain
immersed in the oil.

_Adulteration of Mustard._

Genuine mustard, either in powder, or in the state of a paste ready for
use, is perhaps rarely to be met with in the shops. The article sold
under the name of _genuine Durham mustard_, is usually a mixture of
mustard and common wheaten flour, with a portion of Cayenne pepper, and
a large quantity of bay salt, made with water into a paste, ready for
use. Some manufacturers adulterate their mustard with radish-seed and
pease flour.

It has often been stated, that a fine yellow colour is given to mustard
by means of turmeric. We doubt the truth of this assertion. The presence
of the minutest quantity of turmeric may instantly be detected, by
adding to the mustard a few drops of a solution of potash, or any other
alkali, which changes the bright yellow colour, to a brown or deep
orange tint.

Two ounces and a half of Cayenne pepper, 1-1/2 lbs. of bay salt, 8 lbs.
of mustard flour, and 1-1/2 lbs. of wheaten flour, made into a stiff
paste, with the requisite quantity of water, in which the bay-salt is
previously dissolved, forms the so-called _genuine Durham mustard_, sold
in pots. The salt and Cayenne pepper contribute materially to the
keeping of ready-made mustard.

There is therefore nothing deleterious in the usual practice of
adulterating this commodity of the table. The fraud only tends to
deteriorate the quality and flavour of the genuine article itself.

_Adulteration of Lemon Acid._

It is well known to every one, that the expressed juice of lemons is
extremely apt to spoil, on account of the sugar, mucilage, and
extractive matter which it contains; and hence various means have been
practised, with the intention of rendering it less perishable, and less
bulky. The juice has been evaporated to the consistence of rob; but this
always gives an unpleasant empyreumatic taste, and does not separate the
foreign matters, so that it is still apt to spoil when agitated on board
of ship in tropical climates. It has been exposed to frost, and pa