94 



HOW CROPS GROW. 



Saponification is likewise effected by the influence of strong acids aud 

 by beating with water alone to a temperature of near 400 F. 



Ordinary soap is nothing more than a mixture of stcarate, palmitate, 

 and oleate of potash of soda, with or without glycerin. Common soft 

 soap consists of the potash-compounds of the above-named acids, mixed 

 with glycerin and water. Hard soap is usually the corresponding 

 soda-compound, free from glycerin. When soft potash-soap is boiled 

 with common salt (chloride of sodium), hard soda-soap and chloride of 

 potassium are formed by transposition of the ingredients. On cooling, 

 soda-soap forms a solid cake upon the liquid, and the glycerin remains 

 dissolved in the latter. 



Relations of Fats to Amyloids. The oil or fat of 

 plants is in many cases a product of the transformation of 

 starch or other member of the cellulose group, for the oily 

 seeds, when immature, contain starch, which vanishes as 

 they ripen, and in the sugar-cane the quantity of wax is 

 said to be largest when the sugar is least abundant, and 

 vice versa. In germination the oil of the seed is con- 

 verted back again into starch, sugar, etc. 



The Estimation of Fat (including wax) is made by warming the pulver- 

 ized and. dry substance repeatedly with renewed quantities of ether, or 

 sulphide of carbon, as long as the solvent takes up anything. On evap- 

 orating the solutions, the fat remains nearly in a state of purity, mid 

 after drying thoroughly, may be weighed. 



PROPORTIONS OF FAT IN VARIOUS VEGETABLE PRODUCTS. 



Per cent. 



Meadow grass 0.8 



Red clover (green) 0.7 



Cabbage 0.4 



Meadow hay 3.0 



Clover hay 3.2 



Wheat straw 1.5 



Oat straw 2.0 



Wheat bran 1.5 



Potato tuber. .. ...0.3 



Per cent. 



Turnip 0.1 



Wheat kernel 1.6 



Oat " 1.6 



Maize " 7.0 



Pea " 3.0 



Cotton seed 34.0 



Flax " 34.0 



Colza " .. ...45.0 



6. THE ALBUMINOIDS OR PROTEIN BODIES. The bodies 

 of this class differ from the groups hitherto noticed in 

 the fact of their containing in addition to carbon, oxygen, 

 and hydrogen, 15 to 18 per cent of nitrogen, with a small 

 quantity of sulphur, and, in some cases, phospJionis. 



