First, that the oils used are 100 percent natural, not adulterated in any way.
They are occasionally adulterated with the leaves of Inula Conyza, ploughman's spikenard, which may be distinguished by their greater roughness, their less divided margins, and their odour when rubbed; also with the leaves of Symphytum officinale, comfrey, and of Verbascum Thapsus, great mullein, which unlike those of the foxglove have woolly upper and under surfaces.
Ox and sheep tallow, with the addition of resin, are the primary materials for making the hard yellow or primrose soaps; these tallows are often adulterated.
It is to be observed that with the exception of Burgred's coins and a few anonymous pieces the silver was never adulterated.
The genuine attar of roses is costly and it is frequently adulterated.