640 



SOAP-BUBBLES 



SOBKAON 



textile fabrics. In the West Indies the fruit of 

 .>'_/''/< Saponaria, and in the Kant Indies those 

 of S. emarginatut and S. aUentialus are much used 

 for UiU purpose. The frothy mixture which these 

 fruits make with hot water 'is said to be very ser- 

 viceable for cleaning dyed fabrics which soap w ouli 

 injure. In France silk staffs are cleaned with the 

 seed vessels of S. emarginatus. The seeds of S. 

 Saponaria are made up into rosaries, and were 

 formerly worn in England tipped with gold, silver, 

 &c, as buttons. 



Soap-bubbles. As a form of amusement for 

 children the blowing of soap-bubbles is of great 

 antiquity, and is to be seen depicted on an Etrus- 

 can vase in the Louvre. In their scientific aspect 

 Boap-bubhles and soap-films have been studied 

 specially by Plateau, who, by adding glycerine 

 in a certain proportion to the soap solution, ob- 

 tained remarkably durable films and bubbles. 

 The beautiful play of colours familiar to all is 

 due to the excessive but variable thinness of the 

 soap-film. It is in fact an illustration of the inter- 

 ference phenomenon known as Newton's Rings (see 

 INTKKFKKENCE, NEWTON). If at any part the film 

 becomes thin enough the black spot appears. If 

 tliis black portion is touched the him is shattered 

 at once, although it may in its thicker portions be 

 pierced by a needle without losing continuity. 

 The spherical form of the ordinary soap-bubble is 

 a direct result of the action of Surface-tension 

 (<j.v. ), the geometrical condition being that with 

 given volume the surface must have minimum area. 

 With soap-films formed on frames of wire the same 

 principle holds for given Ixmndary and given in- 

 ternal volume the area must be a minimum. Thus, 

 by a skilful arrangement of soap-films, we may 

 make visible many highly interesting problems in 

 pure mathematics. See Soap-bubbles, by Professor 

 Boys(S.P.C.K., 1890). 



Soap-stone. See STEATITE. 

 Soap-tree. See SOAPBERRY. 



Noapwort (Saponaria), a genus of plants of 

 the natural order Caryophyllaceie, having a cylin- 

 drical or ventricose five-toothed calyx, without any 



outer calyx or 

 attendant brac- 

 tew, five un- 

 divided petals 

 with long 

 claws, ten sta- 

 mens, two stig- 

 mas, and a cap- 

 sule opening at 

 the top by four 

 valves. Some 

 of the species 

 have very ueau- 

 tiful flowers. S. 

 calabrica is one 

 of the most 

 favourite an- 

 nuals of British 

 flower-gardens. 

 Common Soap- 

 1 wort (S. officin- 

 alii) is found 

 on waysides, 

 in thicket*, and on the tanks of streams in most 

 part* of Bwrape, although it isasomewhat doubtful 

 native of Britain. Both the root and the leaves 

 contain Siipnnin (q.v.), in consequence of which 

 they are sometimes employed for washing. The 

 brownish-red colour of the bark of the root, how- 

 ever, is apt to tinge white articles. The root of 

 this plant has also medicinal properties, being 

 a|x-riiMit , resolvent, and alterative. It is sometimes 

 old as l!'-<l Soap root. 



Sompwort (.Saponaria offlcinalii). 



Nearly allied to the genus Saponaria is the genus 

 Gypsophila, some species of which are called Soap- 

 mot, and contain much saponin. Tims, tin- 

 Kgyptian Soap-root (G. etruthiitm), and the Span- 

 ish Soap-root (G. hixpantra), called .//,/,, /,, in 

 Spain, have been employed for washing from time 

 immemorial, and the roots, not having a dark rind, 

 can be used for washing white articles, and are to 

 some extent an article of commerce, being used for 

 silken and other stuffs, the colours of which will 

 not bear the application of soap. The roots of 

 Lychnit dioica, one of the most common British 

 plants, possess the same properties in an inferior 

 degree. The liark of Quillaja sapotiitria, a Chilian 

 tree of the natural order Uosaceo>, contains much 

 saponin, is generally used for washing in Chili and 

 Peru, and there forms a considerable article of com 

 merce. Itissaid togivearemarkahleliistretowool, 

 and to be an invigorating wash for the hair. Some 

 of the tropical South Sea Islands produce a species of 

 vine ( Vitis saponaria ), the stem of which, especially 

 the thicker part, cut into pieces, and softened by 

 cooking on not stones, produces in water a rich 

 lather almost equal to that of soap. See also 

 SOLANUM. 



Sobill. a tributary of the Nile (q.v.). 

 Sobbing is merely a modification of the ordinary 

 movements of respiration excited by mental emo- 

 tions. It is the consequence of a series of short 

 convulsive contractions of the diaphragm, and is 

 usually accompanied by a closure of the glottis, 

 preventing the entrance of air into the lungs. 



Sobiesld, the surname of JOHN III., king of 

 Poland, one of the greatest soldiers of the 17th 

 century, was born at Olesko in Galicia on 2d June 

 1624, his father l>ein castellan of Cracow. He 

 early distinguished himself in the ware in which 

 Poland was at that period almost constant ly 

 eugaged, against the Russians, the Tartars, and 

 the Turks. Upon the last he inflicted crushing 

 defeats at Buczacz (in Galicia) in 1669, and at 

 Choczim (Khotin) on llth November 1673, captur- 

 ing the green standard of Hussein Pasha, com- 

 mander of the Turks, and slaying more than 20,000 

 of his soldiers. In the next year he was chosen 

 king of Poland. A high-minded, brave, and dis- 

 interested man, and a shrewd statesman, he con- 

 ceived it to lie his special mission to contend 

 with all his energy and power against the enemy 

 of Christendom that threatened from the shores 

 of the Bosporus. He again routed the Turks 

 at Lemberg in August 1675, and in 1676 success- 

 fully defied their utmost efforts to storm his 

 entrenched camp near the Dniester. After a truce 

 of five years a breathing-time employed by the 

 sultan to gather fresh armies and war material-- 

 the Turks once more overran Hungary, and even 

 laid siege to Vienna. Sobieski, always swift in 

 his marches, and vigorous and determined in his 

 attacks, hastened to its relief at the head of 18,000 

 Poles. With these, and 50,000 German troojw, 

 who joined him on the way, he smote the 100,000 

 men of the Turkish commander so terribly, on 12th 

 September 1683, that tlie siege was at once raised 

 and the Turks hastened to retire. Sobieski died 

 at his castle of \\ illamo on 17th June 1696. Tl.ii 

 prince was a lover of books and of knowledge, and 

 liimself a clever linguist. 



See his Letter* to his wife (French trmng. 1826) ; Sal- 

 vandy, Hittoirt tin Roi Jean Sobirtki (Paris, 1876); and 

 an article by Lady Verney in the Contemporary (1876). 



Sobral. a town of Brazil, in the state of Ceara, 

 on the Aracaty, 78 miles by rail SS\V. of the sea- 

 port Camossin. Pop. 10,500. 



Sobraon, a village of the Punjab, on the west 

 iank of the Stitlej, opposite which, on the east 

 bank, was fought on 10th February 1846 a most 



