December, 1912. 



KNOWLEDGE. 



The use of water as a cooling agent now came to 

 have general application, and simultaneously sprang 

 up the idea of the '" Worm "' con- 

 denser, one of the earliest forms of 

 which is illustrated by Figure 482. 

 The barrel was filled with cold 

 water, which effected the cooling of 

 the vapours as they passed through 

 the undulating pipe. Special 

 varieties of stills came into use for 

 the manipulation of large quantities 

 of materials : one of the most fre- 

 (juently emploved and interesting of 

 these, fitted up in the "galley 

 furnace " st\le, is seen in Figure 

 481. These early processes, con- 

 the plant along with water 



An early form of Still based on tlie 

 outline of a goose. 



Fir.iKi. 47S. 



A primitive Con- 

 denser made of a 

 layer of wool. 



sisting of introducin 

 into the apparatus, 

 usually heated by a 

 direct fire, displav 

 two disadvantages. 

 Firstly, the plant 

 itself may be easily 

 burnt, with the re- 

 sult that the oil 

 acquires a disagree- 

 able eminTeumatic 

 odour, and secondly. 

 a very careful ad- 

 justment of the amount of water is 

 necessary, seeing that too little renders the 

 oil-containing material more liable to be 

 scorched, while an excess results in partial 

 solution of the small amount of the dis- 

 tilled oil collected along with the relatively 

 large volume of condensed water in the 

 receiver. 



This latter dilute aqueous solution of 

 the oil represents a considerable loss, as 

 it can only be employed as an aromatic 

 water. 



To obviate these disadvantages, the 

 simplest modification consists in sus- 

 pending the plant substance in copper 

 cages, which do not touch the bottom of 

 the still. 



Water is run in, and when sufficient heat is 

 applied, the steam produced by the boiling water 

 carries over with it the essential oil. This process 

 constitutes the basis of the English method (see 

 Figure 48i), and as several of the oils produced in 

 this country are the finest obtainable, the (modified) 

 method must necessarily be a good one. 



In general, however, the process of steam distilla- 

 tion possesses many advantages, and constitutes the the former, the Sponge or 

 means employed iti the large modern German and Spunga method is the one 

 French stills, capable of holding eight thousand to 

 sixteen thousand gallons. The modus operandi is 

 as follows : — 



The charge of material in a suitable state of 

 comminution is placed upon a perforated false 

 bottom ; steam, which is admitted under pressure 



Tlie"R( 



from a pipe coiled beneath the plants, carries over 

 the essential oil through an outlet at the top of the 

 still, into efficient condensers. A spiral of steam 

 pipes lines the interior of the plant-containing 

 portion, and the whole mass of material is con- 

 tinuall}- turned over by means of mechanical stirrers. 

 The mixture of oil and water in the receiver 

 separates : the oil, having a specific gravity lower 

 than that of the water, floats on the surface of the 

 latter liquid, and is removed by suitable means. 



The phenomenon of the high boiling oil distilling 

 with the steam finds explanation in the fact that the 

 atmospheric pressure, acting upon the mixture, is 

 naturally divided between the steam and the other 

 substances, so that the partial pressure upon the 

 latter is accordingly less than the atmospheric 

 pressure. In consequence, the volatility is in- 

 creased. The distillation with steam is, therefore, 

 to be regarded as a special case of distillation in 

 a partial vacuum. 



Two different types of steam distillation apparatus 

 are shown in I'^igurcs 48.5 and 484. Figure 48.5 

 indicates the variety usuall\- employed in this 

 countrv for manipulating small quantities of 

 material, the plants being placed in the upper 

 globular portion, while the steam is generated 

 in the lower reservoir. Figure 484 illustrates a 

 great still of fiftv thousand gallons capacity, used in 

 the largest and most up-to-date essential oil distillery 

 in the world, that of Messrs. 

 Schimmel & Co., Miltitz bei 

 Leipsig. To this firm I offer my 

 heartiest thanks for their courtes\' 

 in allowing me to reproduce from 

 "Die .\etherischen Ole " (Giide- 

 meister & Hoffmann) Figure 484 

 as well as 485, which depicts a room 

 in their distillery, .\lthough the 

 majority of essential oils are ob- 

 tained by a process of distillation, 

 great attention has to be jiaid to 

 the properties of the oils, and 

 to their individual constituents, 

 in deciding what treatment is most 

 advantageous. It is not jjossible 

 more than 



lM(,rKi; 4,s(i. 

 seuhut" air Condfi 



here to do 

 briefly refer to the other 

 methods of isolation, which 

 may be grouped under tv\ o 

 headings, viz. : — Expres- 

 sion and Extraction. 



Of the many and various 

 operations employed and 

 involved in conducting 



most generalh- used, beinf 

 particularly adapted to 

 obtaining the oils of the 

 Citrus family, e.g., orange, 

 lemon, and bergamot. 

 The pieces of the peel of 



Figure 4S1. 



A Still of the " Galley 



Furnace " type. 



