The residents at the fur-posts on the Mackenzie River, have a mineral in use among them, known by the appellation of _white mud_, which is used for whitewashing, and, when soap is scarce, it supplies the place of that article for washing clothes. It resembles pipe-clay, and exists in beds from six to twelve inches in thickness. It is of a yellowish white colour, sometimes with a reddish tinge. On the Arkansas also a similar substance has been met with, called _pink clay_. The clay of the Mackenzie is smooth, and, when masticated, has a flavour, we are told, resembling the kernel of a hazel nut. Sir John Richardson obtained some of this clay in his journey to Prince Rupert’s Land, and had it examined, but could not discover in it any nutritious properties, or detect the remains of infusorial animalculæ, such as are found in other edible clays. The natives of the locality in which this substance is found, eat it in times of scarcity, and suppose that by its use they prolong their lives. There are certain physiological reasons known to us whereby we account for fowls, and other winged bipeds indulging in the singular propensity of swallowing small pebbles, fragments of lime or mortar, sand and clay; but as we cannot apply these same arguments to the cases of other “bipeds without feathers” who indulge in the same propensity, we naturally seek for some signs of nutritious value in the substance itself. In this instance the remote probability of its containing decayed animal matter does not apparently exist, for the microscope detects no infusoria. And unless we argue, as did Hamlet with his friend Horatio, that in this clay are the remains of a previous generation, we can scarce account for its being a good article of food. “Imperial Cæsar, dead and turned to clay, Might stop a hole to keep the wind away;” or dead Indians turned to clay to appease the hunger of their living descendants. Thus, if the imagination may trace the noble dust of Alexander, till we find it stopping a bunghole, may it not also follow this same clay from the bunghole into the veins of a new Alexander? Richardson states that the above is a kind of pipe-clay. If made into pipes for smoking, Hamlet might argue still further, “may we not trace the dust of the dead Indian, till we find a man smoking his weed from the leg or arm of his great grandfather.”