Except by smell, by change of specific gravity, and by deterioration of drying properties, these adulterations are difficult to detect.
The black variety of cochineal is sometimes sold for silver cochineal by shaking it with powdered talc or heavy-spar; but these adulterations can be readily detected by means of a lens.
Soon after the apothecaries were formed into a separate company they took into consideration means to prevent the frauds and adulterations practised by the grocers and druggists, and, to remedy the evil, established a manufactory of their own in 1626 so that they might make preparations for their own members.
The frauds and adulterations were probably due in part to the apothecaries, for Dr Merrit, a collegiate physician of London, stated that " such chymists which sell preparations honestly made complain that few apothecaries will go to the price of them."
Linseed is subject to extensive and detrimental adulterations, resulting not only from careless harvesting and cleaning, whereby seeds of the flax dodder, and other weeds and grasses are mixed with it, but also from the direct admixture of cheaper and inferior oil-seeds, such as wild rape, mustard, sesame, poppy, &c., the latter adulterations being known in trade under the generic name of " buffum."