336
ELEMENTS OF MATERIA MEDICA.
Composition. —The following is the composition of several varietiesof soap:—
OLIVE OIL SODA SOAP.
ANIMAL OIL POTASH SOAP.
Marseilles
Marbled.
Foreign
London-made
Castile,verv dry.
Castile,very dry.
Soda .
6
6
9-0
10*5
.. 9-0
Stearic acidOleic acid .
.9-20
.59.20
£ 60
64
76-5
75-2
Fatty acids.
.. 43-7
Water.
34
30
14-5
14*3
Water.
.. 47*3
Olive oil soda soap.. lOO'OO
100
100
100.0
100*0
Animal oil potash soap
..100-0
(Braconnot.)
(D’Arcet.)
(Thenard)
(Ure.)
(Ure.)
(Ure.)
For analyses of other kinds of soap I must refer the student to Ure’sDiet, of Chemistry, and Gmelin’s Handb. d. Chemie . The atomic con-stitution of soap cannot be determined with accuracy, on account of thegreat variation in the quantity of water. The relative proportion of acidand base appear to be nearly one equivalent of the fatty acid to two ofthe alkali. Thus, olive oil soda soap may be regarded as a compound ofone equivalent or 518 parts of oleic acid, and two equivalents or 64 partsof soda, exclusive of the water and the small quantity of stearate (ormargarate) of soda present.
Purity. —The adulterations of soap are excess of water, lime, gypsum,or pipe-clay. The first may be known by the consistence of the soap,and the great loss of weight which this substance undergoes in dry air.The other impurities may be detected by alcohol, which leaves themundissolved.
Physiological Effects, (a.) On vegetables. —Soap, used as a manure,appears to promote vegetation (Decandolle, Physiol. Veget. p. 1343).
(b.) On animals. —It does not appear to be poisonous to animals.Veterinarians employ it as a diuretic, and, in large doses, as a purgative.
(c.) On man. —Soap acts very much like the alkalies ( vide Potass.®,p. 275). Its local operation, however, is much less energetic than eitherthe caustic or even the carbonated alkalies. Hence it may be adminis-tered in considerable doses without causing irritation or inflammation.When swallowed it very readily palls the appetite and disturbs the diges-tive functions, and in these qualities it is more powerful than the alkalies.Perhaps these effects depend on the fatty acids which must be disengagedin the stomach, in consequence of the union of the alkali of the soapwith the free acids of the gastric juice. Probably the fatty acids becomemore or less completely digested, for soap acts on the general system likethe alkalies; it promotes the secretion of urine, and communicates alka-line properties to this fluid. In large doses, soap acts as a purgative.I knew an idiot who had frequently eaten large lumps of soap without anyill effects; and I have heard of a pound of it being swallowed for awager!
Uses.— As an antacid , soap is employed in poisoning by the mineralacids: it should be administered in the form of a strong solution, whicheffectually neutralizes the acid without acting as an irritant. So also inthose forms of dyspepsia which are attended with an excessive formationof acid, soap may be usefully employed to neutralize it. External partsburnt with the strong mineral acids, or with phosphorus, should be■washed with a solution of soap. As a lithontriptic, soap has been usedin those forms of lithiasis in which uric acid or the urates prevail.A mixture of soap and lime-water was once considered a most powerful