s \.i\V, RED. 



SOAP MANUFACTURE. 



36 



mm or herbage at their base, the atmosphere immediately around 

 being chillnl by the now*, and Ui lummer un rarely warming the 

 oil. In the vicinity of Kinchinjhuw, 21,000 feet high, and where the 

 mean level of perpetual mow i* 19,000 feet, coinciding, probably, with 

 a mean temperature of 20, the glacier* do not descend below 16,000 

 feet, but a green sward of vegetation creeps up to their base*, and 

 herb* grow on the patches of earth they carry down, while dwarf 

 rhododendrons cover the moraines. Dr. Iluoker conclude* on this 

 Ktibject with the following general statement : " Looking eastward or 

 westward on the map of India, we perceive that the phenomenon of 

 perpetual snow is regulated by the same laws. From the longitude of 

 Upper Assam in 95' E. to that of Kashmir in 75* ., the lowest limit 

 of perpetual snow is 15,500 to 10,000 feet, and a shrubby vegetation 

 affects the most humid localitie* near it, at 12,000 to 14,000 feet. 

 Receding from the plains of India and (xmetrating the mountains, the 

 climate "becomes drier, the mow-line rises, and vegetation diminishes, 

 whether the elevation of the land increases or decreases; plants 

 reaching 17,000 and 18,000 feet, and the snow-line 20,000 feet. To 

 mention extreme i inc : the mow-level of Sikkim in latitude 27 30' 



is at 16,000 feet, whereas in latitude 85 SO' Dr. Thomson found the 

 snow-line 20,000 feet on the mountains near the Karakoram pass, and 

 vegetation up to lS,. r >00 feet features I found to be common also to 

 Sikkim in latitude 28*." 



The progress of physical geology brings before us, from time to 

 time, the conditions of the earth's surface at former periods. An 

 example of this, probably involving the consideration of the great 

 extension of snow and ice in the northern hemisphere, southward 

 from the arctic regions, at what has been termed the glacial epoch, as 

 alluded to in several former articles, is stated by Dr. Hooker nearly in 

 the following terms : Were the snow-level in the Dingcham province 

 of Tibet as low as it is in Sikkim, or 15,000 feet, the whole of 

 Tibet, from the Donkia mountain northwards to the Yoni-Tsampu 

 river, the average direction of which is west and east nearly in the 

 latitude of 29* 10', " would be everywhere intersected by glaciers and 

 other impassable barriers of snow and ice, for a breadth of fifty miles, 

 and the country would have no parallel for amount of snow beyond 

 the Polar circles. It is impossible to conjecture what would hare 

 been the effects on the climate of northern India and central Asia 

 under these conditions. When, however, we reflect upon the evidences 

 of glacial phenomena that abound in all the Himalayan valleys at and 

 above 9000 feet elevation, it is difficult to avoid the conclusion that 

 such a state of things once existed, and that at a comparatively very 

 recent period." Valuable information on this subject, as well as on 

 the philosophy of the snow-line as at present existing, will be found iii 

 Mr. \V. Hopkins's paper, " On the causes o{ changes of climate," 

 ' Quart Journ. of Geo. Soe.,' voL viii.,p. 76-87. 



SNOW, RED. [See NAT. HIST. Uiv.j 



SNUFF. [TOBACCO.] 



SOAP MANUFACTURE. Soap originally meant the compounds 

 derived from the union between fatty bodies and the alkalies potash 

 and soda. Although the name is still usually thus limited in its mean- 

 ing, it has nevertheless been extended to compounds of oleaginous bodies 

 with some earthy and metallic bodies, having but few properties in 

 common with soap properly so called. 



Propertia. It has been found by Chevreuil that different varieties 

 of fatty matter consist chiefly of two kinds : one hard, to which he 

 gave the name of tlearin ; and the other soft, which he termed olfin. 

 He also discovered that stearin is compossd of stearic acid and a pecu- 

 liar principle which, on account of its sweet taste, he named glycerin ; 

 and it was further proved by his experiments that olein consists of 

 oleic acid and glycerin. Stearin is therefore a stearate of glycerin, and 

 olein an oleate of the same substance. When, in the manufacture of 

 soap, an alkali (soda, for example) is heated with tallow, the soda 

 gradually dislodges the glycerin from combination with the stearic and 

 oleic acids, and by combining with them, forms soap, or, in other words, 

 a compound of stearate and oleate of soda, and the glycerin remains in 

 solution. 



In vegetable fat oils olive-oil, for example the glycerin is combined 

 with margaric and oleic acids, forming margarate and oleate of glycerin ; 

 and, consequently, soap made with this oil is a margarate and oleate of 

 soda, instead of a stearate and oleate of this base. 



The soaps which have the alkalies for their bases ore soluble in water, 

 though the solution is in general milky ; they are also soluble in alcohol, 

 and the solution is used frequently as a test of what is called the 

 kanlmu of water. [SoAi'-TKST.] Acids also decompose soaps, and 

 though the effect is apparently similar, yet it is in reality different : 

 thus when sulphuric acid is added to soap, a white precipitate is formed, 

 but thin is merely the fatty acid which the soap contained, and shows 

 the change which the fat employed has undergone ; it is either stearic, 

 oleic, or margaric acid, Ac., or a mixture of two or more of them. 

 Sulphate of soda remains in solution when a soda soap has been thus 

 decomposed. There are certain preparations used in medicine under 

 the names of emulsions and liniment*, which are obtained by merely 

 agitating either ammonia, potash, soda, or lime-water, with oil. The 

 tir.-t of these is an ammoniacal soap; the second and third are imperfect 

 alkaline soaps; and the fourth is an earthy soap to which barytes and 

 M r. .in in- water form compounds nearly analogous ; these earthy soaps are 

 insoluble in water, or nearly so. Metallic soaps are formed by heating 



certain metallic oxides, as those of lead, mercury, and bismuth, with 

 fatty matter ; glycerin is separated, as has already been mentioned, and 

 the metallic soaps formed are insoluble in water. The only soap of 

 this kind extensively employed is that of oxide of lead, which is largely 

 used under the name of diachylon, or lead plaster. 



ManHfacturr. Some of the soap-factories of the present day carry 

 on operations with the aid of considerable chemical and mechanical 

 skill. There is, however, not much that requires description here. 



Mottled soap, a kind much used in England, is made of tallow, 

 kitchen stuff, soda, water, and a little salt. The tallow principally 

 employed is brought from Russia, and arrives in a solid state in barrels; 

 it is tolerably pure, and is ready for use at once. The impure grease 

 known as kitchen-stuff requires much heating, straining, anil purifying 

 before it is fitted for use ; and even then it is not employed for the 

 better soaps. The alkali formerly used, as has already been stated, 

 was obtained from kelp and barilla; but the carbonate of soda obtained 

 from common salt is now almost exclusively used. The soda being 

 required almost in a caustic state, the carbonic Mid is driven off for 

 the soap-maker's -purposes. The caustic soda is dissolved in water to 

 form a try or lye. The ley is pumped into boilers, and mixed with the 

 fatty substances. Steam-heat is applied, and the mixture is boiled 

 until the fat has combined with all the alkali of the ley. The spent 

 ley is pumped up, fresh ley is introduced, and the boiling proceeds. 

 This is repeated several times, a stronger ley being used each time than 

 before. When the soap is nearly finished, the " mottling " is given by 

 sprinkling a small quantity of very dense ley ; this percolates slowly 

 through the mass, leaving dark-coloured veins in its track. When the 

 soap is finished, it is laded into buckets, and thence transferred 

 to frama. These frames are upright oblong boxes, made cither of 

 wood or iron, and easily taken to pieces. The soap, when the frames 

 ore full, is allowed to cool and solidify. Each frame being taken to 

 pieces, the mass of soap, sometimes weighing as much as three or four 

 thousand pounds, is exposed to view. It is cut up into slabs or 

 layers by a wire being drawn through it, following the marks of certain 

 gauge-lines. The application of a similar wire in a different way after- 

 wards separates the slabs into bars about 15 inches long, 3 inches wide, 

 and 3 inches deep. 



Curd or while soap is made nearly in the same way as mottled, but 

 with a more careful selection of ingredients, and a better management 

 of some of the processes. 



Yellow soap is distinguished from the others by the large amount of 

 resin and palm-oil contained in it. The casks of palm-oil, as brought 

 from Africa, are placed over a trough with the bung-hole downwards ; 

 the steam-pipe is admitted, and the melted substance flows out. The 

 oil is bleached by a chemical process, and then the soap-making pro- 

 ceeds as before. The resin and the palm-oil both serve the purpose of 

 tallow, and are the cause of the relative cheapness of yellow soap. 



Soft soap, used principally in the woollen manufacture, is made 

 chiefly of oil and potash. The oil may be whale, seal, olive. Unseed, 

 or any that comes most readily to hand, and is combined with a little 

 tallow to increase the stiffness. Soft soap is not shaped in frames, lut 

 is poured at once into barrels or casks. 



fancy soaps, as they are called, such as are sold by perfumers, are 

 generally made from good white soap, rcuicltod, and modified by the 

 addition of perfumes, &c. 



Dr. Normandy in 1841 patented on invention for using up all kinds 

 of gums and resins in soap by the addition of sulphate of soda. He 

 made hard soap cheap by that means ; but his operations were checked 

 by the Excise insisting on the same rate of duty as was paid for 

 the high-priced soaps. His patent, not having been a profitable one, 

 was renewed in 1855 for three years. 



A substance called ioap bark was brought to Europe from some 

 tropical country in 1859. It is black without, and y.ll.>ui-h white 

 within, very heavy and dense. When the white layers are macerated 

 in water, they produce an emulsion which, when mixed with oil, may 

 be used as soap. 



>'..;( '/'nnli . The soap manufacture is one of considerable importance. 

 The principal seats in England are Liverpool and Runcorn, London, 

 Brentford, Bristol, and Hull. Nearly three-fourths of the total quantities 

 of soap are made at these places ; but there are also manufactories of 

 considerable extent at Bromsgrove, Newcastle, Gateshead, Warrington, 

 and Plymouth. In Scotland, two-thirds of the total quantity \ 

 are made at Glasgow and Lcith. 



In 1711 an Excise duty of Id. per Ib. was first imposed on all soap 

 made in Great Britain, which was raised in 1713 to IJrf. peril). In 

 1782 the duty was again increased, and a distinction was, for the first time, 

 inadu between hard and soft soap, the duty on the i> ~\d-, 



and on the latter Ijrf. per Ib. In 1816 hard soap w.-w subjected to a 

 duty of 3</. per Ib. In 1833, the duty v. Hi. mi hard soap, 



and Id. per Ib. on soft. The interference of tL> i the manu- 



facture of soap was, until recently, exceedingly arbitrary and v. \atious; 

 but in the 'Seventeenth Report of the Commissioners of I 

 Inquiry,' 1835, the discontinuance of the system of survey which then 

 existed was recommended. , The act 3 and 4 Viet. c. 49, passed in 1840, 

 repealed seventeen other acts, so far as they concerned the making of 

 Knap. The article may now be made in ;my way or ot any material 

 which the manufacturer thinks most judicious, as the Excise does not 

 interfere with the process of manufacture. 



