This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
"Soap. - The well-known action of alkalies upon the cuticle, and upon the horny tissues generally, explains why soaps have been so commonly employed for therapeutical purposes, as well as to cleanse the healthy skin. It seems as though instinct leads men to use water and soap in all cutaneous diseases in which epidermis is formed in excessive quantity, and accumulates in the form of scales upon the surface. It is, therefore, not surprising that we find soap praised as a local remedy for psoriasis; and the praise is in fact deserved, provided that the right kind of soap be employed, and in the right manner. Common washing soap (soda-soap), used in the ordinary way, as for washing hands, will not, indeed, answer our expectations, for by it the disease is either not cured at all, or only after a very long time. But if potass-soap be employed, and in a methodical and energetic manner, very successful results may be obtained.
"I will speak first of the soap itself, and then of the way in which it is to be applied. And, in the first place, I must remark that, in endeavoring to procure a good potass-soap, one should not go to the apothecary's shop, but, if possible, to some manufactory in which it is made on a large scale. Pfeuffer, and other medical writers, have, indeed, taken the trouble to lay down a formula for the preparation of soap in the pharmaceutical laboratory, but they have forgotten that saponification is not to be effected by merely mixing certain quantities of alkali and fat together, and that it is important to be acquainted with practical details known to those only who are engaged from year to year in the soap manufacture. Repeated observation has taught me that most variable effects are produced by soft soap prepared by these methods in the apothecary's shop. At one spot it will completely denude the skin of its epidermic covering, and expose the corium; in another place it has no more effect than so much oil. In the first case, it produces a number of painful excoriations, by which further treatment is interfered with; in the second case, it is altogether inert. In asserting that it is not advisable to use potass-soap prepared by the apothecary, I do not, however, mean to say that what is procured at the druggist's shop is never well made. On the other hand, I am quite aware that the soap of commerce is by no means necessarily free from faults, for it very often contains small carbonaceous particles and ashes, which render it gritty, and make it very apt to produce irritation when applied to the skin.
"Good soft soap, or potass-soap (Schmierseife, grune Seife, sapo viri-dis, sapo kalinus, savon vert), should be somewhat thicker than syrup, or of about the consistence of Roob Laffecteur, so as not to flow out when the jar containing it is turned upside down. It should be of an olive-green or brown color, and should have an acrid alkaline taste when put on the tongue. It ought not to be at all gelatinous, but rather of a pulpy character, and perfectly homogeneous. It should have no rancid smell. It should be dissolved by alcohol, without any residue of consequence. Lastly, no particles of sand should be discoverable in it, when it is rubbed down between the fingers.
"To remove the unpleasant smell which always belongs to potass-soap, it may be dissolved in alcohol (in the proportion of two parts of soap to one of alcohol), and this solution, after being filtered or allowed to settle, may be scented by the spiritus lavandulae, or any other aromatic spirit. In this way all the therapeutical effects of the soft soap may be obtained, while its disagreeable odor is avoided, and the particles of sand which it contains are got rid of. To distinguish this solution from the ordinary spiritus saponatus, made from soda-soap, I term it the spiritus saponatus ka/inus.
"In the use of this liquid, or of the potass-soap itself, the main points to be attended to are, that the application should be brought into immediate contact with the surface of the skin, and be left there for a long time. It is not sufficient to rub in the remedy and immediately afterward to wash it away. The soap must be allowed to remain upon the diseased part for several days, and sometimes even for weeks together. It must, in fact, be employed in the same way and on the same principles on which we should make use of water-dressing or of a lotion (in Gestalt und nach dem Principe von Umschlagen). There is a very wide difference between rubbing in an ointment of which the constituents are expected to penetrate the different layers of the skin, and to be absorbed by the vessels and thus to enter the circulation, and using a remedy whose main action is supposed to be to soften and macerate the epidermis, or to destroy it. The longer such a remedy is left in contact with the cutaneous surface, the more certainly will the object of its use be attained.
"It was in the so-called "English method' of curing scabies that the practice was first introduced of wrapping patients stark naked in blankets, and rubbing sulphur ointment or soft soap over the whole body. It was then observed that by this plan of treatment the epidermis was extensively softened and destroyed, and this naturally led to the employment of the same or a similar, method in other cases of cutaneous disease, particularly those which, like psoriasis, are widely diffused over the surface of the skin. Thus Pfeuffer recommends that the patient should be wrapped for six days at a time in blankets, and should be rubbed twice daily with soft soap. Of this he gives him eighteen ounces, divided into six portions, three of which contain four ounces, and three two ounces each. On each of the first three days four ounces are used, half that quantity being in the morning rubbed over all parts of the body by means of pieces of flan-nel or flesh brushes, and the remainder being applied in the same way at night. During the last three days of the treatment an ounce is sufficient for each time of application - for not only is the epidermis itself now to a great extent softened, but the blankets are impregnated with a good quantity of the soap. At the end of the six days Pfeuffer advises that the patient should be allowed to take a bath, and this completes a course of the 'soap cure.'
"In some of the less severe cutaneous diseases, such as pityriasis versicolor, herpes tonsurans, etc., in which the morbid products occupy only the most superficial layers of the cuticle, a cure may be effected by making the patient lie in blankets for six days, and rub in soap in the manner above described. But psoriasis, even in the mildest form, is not one of the complaints which can thus be removed by a 'soap cure' of six days' duration.
** A further disadvantage of this method of Pfeuffer is that its completion within the period named is merely nominal. The patient is unable to get up for several days afterward, for he can generally neither walk, nor stand, nor move his arms. The skin over the flexures of the joints is, in fact, so tense and painful, that he cannot extend his limbs.
"These defects, which must be apparent to every one who employs the soap-cure in practice, have caused me to modify somewhat this method of treatment. For instance, in a case of psoriasis diffusa inveterata, in which the whole surface of the body is affected, I have soap rubbed in twice a day, in a quantity which varies with the age and size, and also with the susceptibility (Vulnerabilitat) of the patient, but which is generally from about two to four ounces daily. Young women, in whom the skin is delicate and contains but little pigment, naturally require a smaller amount than strong, heavy adults, whose epidermis is of a dark color. It is, however, essential that the soap should be firmly rubbed into each individual patch of psoriasis by means of a piece of flannel or a brush, till the accumulated masses of epidermis are removed, and a little blood is seen to ooze from the red base which has thus been exposed. To diminish the painfulness of this procedure, the body should be divided into regions, and a different region should be especially attended to each time the soap is used. For instance, on the first occasion, some particular part, such as the right arm and forearm, should be rubbed forcibly till it bleeds, while the remedy is only applied gently to the rest of the body. Next time, on the other hand, the more energetic frictions may be limited to the left upper limb, and so on, until at the end of six or eight days every part of the cutaneous surface has been rubbed in such a way as to produce slight bleeding. Within the period named, then, according to the severity and extent of the affection, the frictions are completed; but the patient must not be permitted to take a bath, or to give up lying in the blanket impregnated with soap. In this he must still remain for at least three or four days after the rubbing is discontinued, in fact leaving it only when extensive desquamation has commenced, so that the whole cuticle is peeling off in large lamellae. Moreover, until this takes place, he must not be allowed to take a bath, to change his bed- and body-linen, or to dress himself. It is, however, in but few cases that even this energetic course of treatment effects the result aimed at, the cure of the psoriasis. But the repeated employment of the same treatment, or a combination of it with other procedures to be hereafter described, will nevertheless often be successful.
"Moreover, I frequently apply the soft soap without wrapping the patient in blankets. In cases of psoriasis and other skin affections I often have this substance forcibly rubbed into the skin, in order to soften and remove the masses of epidermis, and thus to smooth the way for the employment of other remedies, and enable them to produce their full effects.
"When psoriasis affects only a few parts of the body, such as the elbows and knees, or is confined to any other special region, my usual plan is to make a sort of plaster by spreading soft soap, like an ointment, over pieces of flannel, and to apply these to the spots affected, until they soften the epidermis and remove the masses of scales:
"The variety of psoriasis in which I have found the soft soap (and particularly the spirit us saponis kalinus) most useful is that affecting the hairy scalp. I must, however, mention the remarkable fact that the disease is much less obstinate and yields more readily to treatment when it occupies the head and face than when it is seated on other parts of the body. In fact, in cases of psoriasis confined to the head I have never failed to cure the complaint pretty quickly by having the part repeatedly washed with the spiritus saponatus kalinus, without making use of any other remedy.