SNA 



SOI 



SITAIT. FLOWEH. Phaw'nlm cararn'lla 



SXAKE GOURD. Trichos(i')if/i,-s. 



SXAKE ROOT. Arislolo'chia serpen- 

 ta'ria. 



SNAKE WOOD. Cecro'pia. 



SNAPDRAGON. Antirrhi'num and 

 Sile'ne anlirrhl'na. 



SNEKZEYTOTVT. Achilk'a Pta'rmica. 



SNOW is one of the gardener's best 

 shelters, and should never be removed 

 from his out-door crops. It prevents 

 heat from radiating from them ; pro- 

 tects them from freezing, drying blasts, 

 and, being a bad conductor of heat, 

 thus prevents its escape from them. 

 We have never known the surface of 

 the earth, below a covering of snow, 

 colder than 32, even when the tem- 

 perature of the air above has been 28. 



SNOWBALL TREE. Vibu'rnum O'pulus. 



SNOWBERRY. Chioco'cca. 



SNOWDROP. Anc'mone sylve'stris and 

 Gala' nt hits. 



SNOWDROP TREE. Hale' da. 



SNOWFLAKE. Leuco'jum. 



SOAP-BOILER'S ASHES. See Ashes, 



SOAPWORT. Sapona'ria. 



SOBRA'LIA. (Named after F. M. So- 

 bral, a Spanish botanist. Nat. ord., 

 Orchids [Orchidacese]. Linn., 20-Gy- 

 nandria 1-Monandria.} 



Stove orchids, grown in pots. See Orchids. 

 S. deco'ra (comely). Various. July. Gua. 

 temala. 1836. 



dicho'toma (two-ranked). Rose, purple. 



March. Peru. 



Klia'strum (Lily-flowered). White. July. 



Guiana. 1840. 



macra'ntha (large-flowered). 6. Crimson. 



September. Guatemala. 1842. 

 _ sple'ndens (splendid). 3, Crim- 

 son. September. Guatemala. 1846. 



se'ssilis (stalkless). Pink. December. Peru. 



1840. 



viola'cea (violet). Violet, white. July. 



Merida. 



SOIL. However varying in the pro- 

 portions, yet every soil is composed of 

 silica, alumina, Lime, magnesia, oxide 

 of iron, salts, and animal and vegetable 

 remains. A fertile soil is one which 

 contains such a proportion of decom- 

 posing matter and of moisture as to 

 keep the crop growing upon it always 

 supplied with food in a state fit for the 

 roots to absorb, yet not so superabund- 

 antly as to render the plants too luxu- 

 riant, if the object in view is the pro- 

 duction of seed ; but for the production 



of those plants whose foliage is the 

 part in request, as spinach, or of edible 

 bulbous roots, as onions, Avhich have u 

 small expanse of leaves, so as to be 

 almost entirely dependent upon the soil 

 for nourishment, there can scarcely be 

 an excess of decomposed matter pre- 

 sented to their roots. 



A subsoil of gravel, mixed with clay, 

 is the best, if not abounding in oxide 

 of iron; for clay alone retains the mois- 

 ture on the arable surface, in too great 

 an excess ; and sand or chalk, on the 

 contrary, carries it away too rapidly. It 

 is, however, evident, that to insure these 

 desiderata in any soil, at all seasons, is 

 impossible ; and it is manifest that a 

 soil that would do so in one climate 

 would fail in another, if the mean an- 

 nual temperature of them should differ, 

 as well as the amount in inches of rain 

 which fall during the same period. 

 Thus, in the western parts of England, 

 more than twice as much rain occurs 

 ! as in the most eastern counties, or in 

 the proportion of forty-two to nineteen; 

 a soil in the east of England, for any 

 given crop, therefore, may be richer 

 and more tenacious than the soil re- 

 quired for it on the western coast. 



Alumina (clay) imparts tenacity to a 

 soil when applied ; silica (sand) dimi- 

 nishes that power ; whilst chalk and 

 lime have an intermediate effect. They 

 render heavy soils more friable, light 

 soils more retentive. These simple 

 facts are important; two neighbouring 

 gardens, by an interchange of soils, 

 being often rendered fertile, which be- 

 fore were in the extremes of tenacity 

 and porosity. 



In affording warmth to plants, the 

 earth is of considerable importance, 

 and the power of accumulating and 

 retaining heat varies as much in soils 

 as the proportions of their constituents. 

 Sir Humphrey Davy found that a rich 

 black mould, containing one-fourth of 

 vegetable matter, had its temperature 

 increased, in an hour, from 65 to 88 

 by exposure to the sunshine, whilst a 

 chalk soil was heated only to 69 under 

 similar circumstances. But the first, 

 when removed into the shade, cooled in 

 half an hour 15 ; whereas the latter 

 lost only 4t p , This explains why the 



