185 



THE AIMS OF SOIL BACTERIOLOGY. 



It now remains to indicate the aims of Bacteriology in connection 

 with Agriculture. These are shortly as follows : — 



1. To encourage a definite multiplication of the nitrifying organisms 

 found already in the fields, by adding substances that will enable them 

 to retain their vitality and vigour after their activity ceases for the 

 want of nitrogenous material ; and in case of their abs 'iice from a soil 

 to transplant them thereto, if this can conveniently be done, by add- 

 ing soil impregnated with the desired bacteria. 



2. To secure by the growth of plants favourable to nitrogen-fixing 

 organisms an enrichmeut of the soil by nitrogenous compounds; and 



3- To counteract the sudden and excessive development of the deni- 

 trifying organisms, in order to prevent loss of fertilising substances by 

 means of these latter. 



OIL OF LEMON.* 



'Oil of Lemon is obtained from the fresh peel of the Genoese lemon 

 (Citrus medica, Linn, var. B limonum, Hook, f.) being contained in 

 numerous large oil-glands, imbedded in the tissue of the epicarp. 



The greater part of the oil of commerce is produced in Sicily, chiefly 

 in the Messina and adjacent districts, and in th^ province of Palermo. 

 A large quantity is produced in Calabria, and exported from Reggio, 

 whilst the north of Italy and south of France also supply the market 

 with oil. It is obtained during tbe winter months, fro:n Xovember to 

 March or April, that collected in November and Decembc, usually 

 being of the finest quality. In Sicily and Calabria — i.e., the chief oil-of- 

 lemon districts — the oil is collected by the sponge process, the peel 

 being cut off the lemons in strips, which is then pressed against a 

 sponge in such a way that the oil-glands are broken, and the oil forcibly 

 ejected; as the sponge becomes saturated it is sqeezed to remove the oil 

 which has accumulated. In the north of Italy and th^ south of France the 

 oil is collected by the ecuelle process, the fruit being rotated rapidly in 

 a tinned-copper saucer (ecuelle), 20 to 25 cm. in diameter, which is 

 covered inside with short spikes from 6 to 8 mm. long ; the oil-glands 

 are broken by the spikes and the oil flows through a hole in the bottom 

 of the saucer into a collecting tube beneith, which is periodically 

 emptied. Machine processes are employed in some districts for ex- 

 tracting the oil, and simple distillation or expression in bags inordinary 

 presses are also resorted to on occas on. In both the sponge and 

 ecuelle processes the remaining traces of oil in the exhausted peel are 

 extracted by placing the peel m hot water and skimming ofi the oil 

 as it rises to the surface, or the peel may be subjected to distillation; in 

 either case the oil is of inferior quality, its value bein^ impaired by 

 the application of heat. Oil of lemon possesses stimulant and carmina- 

 native properties, but it is chiefly used as a flavouring agent. ♦ 



* Pharmaceutical Journal, Sept, 16th, 1900. 



