SOD 



SOI 



" All new soaps contain a consid- 

 erable portion of adhering water, a 

 great part of wliicii they lose when 

 kept ill a dry place ; hence the econ- 

 omy and excellence of old soap ; and 

 lience the dealers in soap generally 

 keep it in a damp cellar, that it may 

 not lose weight by evaporation ; or, 

 as it is said, sometimes immerse it in 

 brine, which does not dissolve it, but 

 keeps it in its utmost state of liu- 

 miditv." 



SOAPER'S WASTE. The refuse 

 of the soap-works has been much 

 used as a manure. The nature of 

 the manure depends on the use of 

 ashes or soda ash in the manufac- 

 ture : in the first case, it is a very 

 valuable amendment ; in the latter, 

 considerably less so. The first con- 

 tains a large quantity of ash, the 

 chloride of potassium ; the second 

 contains but little soda salts, and 

 ■when barilla is employed, the ash is 

 merely calcareous matter : of the lat- 

 ter ashes, in the fresh state, from 60 

 to 200 bushels have been used on 

 grass lands with great effect. If 

 ashes and common salt have been 

 used, 10 to 20 bushels of refuse will 

 be enough. The gelatinous substance 

 remaining after the separation of the 

 soap is called glj'cerine, and does not 

 contain nitrogen ; it is not, therefore, 

 of much moment alone. 



SOAPSTONE, STEATITE. A 

 gray, soft mineral, consisting of sili- 

 cate of magnesia, coloured by two 

 and a half per cent, of iron. 



SOBOLE. An underground creep- 

 ing stem. 

 SOD. A turf of grass. 

 SODA, PROTOXIDE OF SODI- 

 UM. An alkali very analagous and 

 isomorphous with potash. Equiva- 

 lent, 31 31, or 23 31 sodium and 8 

 oxygen ; symbol, Na O. It is con- 

 stantly found, m the ashes of plants 

 performing the same function as pot- 

 ash ; but in the vine and some other 

 plants it is not equally serviceable. 

 In the mineral kingdom it is abun- 

 dant as a silicate, but especially in 

 the form oi chlonde of sodium, or sea 

 salt (see Soli) ; the nitrate, which 

 is an important manure, is also 



abundant in certain places (see Ni- 

 trates). 



Kelp, barilla, and soda ash all owe 

 their value to the carbonate of soda, 

 which is used in making hard soaps. 

 The carbonate of soda resembles 

 pearlash very closely in its properties, 

 but is less active. 



SOIL. "The nature and compo- 

 sition of soil, and, consequently, its 

 greater or less aptitude to the growth 

 and maturity of vegetable produc- 

 tions, depend chieHy on the propor- 

 tion and mechanical structure of the 

 various substances of which it con- 

 sists. When the soil is favourable 

 to the chemical action by which the 

 elements are combined to form ve- 

 getable substances, and admits that 

 quantity of air and moisture without 

 which this chemical action cannot 

 take place in any given climate or 

 temperature, vegetation goes on rap- 

 idly, and all the plants which are suit- 

 ed to the climate grow in the great- 

 est perfection and bear abundant 

 fruits. 



" It is not, however, very frequent- 

 ly the case that a soil possesses all 

 those qualities on which great fertil- 

 ity depends. So many circumstan- 

 ces must concur to make a soil high- 

 ly fertile, that the great majority of 

 soils can only be made to produce 

 abundantly by being improved by art 

 both in their texture and composi- 

 tion. Hence the practice and sci- 

 ence of agriculture, which is founded 

 on experience, but to which every 

 progress in science also affords great 

 assistance, by the additional light 

 which every new discovery throws 

 on the true theory of vegetation. 



" There are various modes of dis- 

 tinguishing soils, without here enter- 

 ing into a minute analysis (see Anal- 

 ysis) oi their component parts. The 

 simplest and most natural is to com- 

 pare their texture, the size and form 

 of the visible particles of which they 

 are composed, and to trace the prob- 

 able source of their original formation 

 from the minerals which are found 

 around or below them, or the rocks 

 from which they may have been slow- 

 ly separated by the action of the el- 



727 



