This section is from the book "A Practitioner's Handbook Of Materia Medica And Therapeutics", by Thos. S. Blair. Also available from Amazon: A Practitioner's handbook of Materia Medica and Therapeutics.
Kaolinum, Kaolin or China Clay. One of the inscrutable acts of the revisers of the U. S. P. was to make this native silicate official as an ingredient of "Cataplasma kaolina," an official imitation of the proprietary paste of kaolin, glycerine, and antiseptics. Following this, in the very excellent but plenarily inspired series of articles in the Journal of the American Medical Association, all the proprietary mud poultices (uninspired and non-canonical) are denounced as heretics and deceivers of the elect. As a practical matter of fact, no druggist will ever care to make up a batch of the official cataplasma in a mortar more than once. Furthermore, it cannot be well made except by machinery. It needs very little study of the ingredients of these "mud poultices" to define their limits in therapeutics. While the literature issued concerning them is utterly ridiculous in some of its phases, still these preparations have a very positive usefulness in many conditions not very markedly inflammatory or painful. Personally, I object to using heavy clay poultices upon the chest in severe diseases like pneumonia. The troublesome details of application and removal, as well as the weight, distress the patient, and, after they are removed, he is very apt to chill. I use a rather homely plaster in these cases of chest trouble. Take 1/2 K each of capsicum and Scotch snuff and 2 K of powdered lobelia seed. Triturate this well together and spread more or less thickly (according to patient's age) upon a cloth spread with lard or vaseline, and place upon the chest; or this powder can be mixed with mustard and hot water, or ground flaxseed and boiling water, and applied as a wet poultice. These agents have a real medicinal influence, whereas the action of clay and glycerine is very slight in severe disease.