346 CHEMICAL DISCOVERY AND INVENTION 



still so that the steam may pass through the leaves, flowers, or 

 other matters which are supported just above by means of a 

 wire screen resting on a frame, not shown. The condenser may 

 consist of a number of tubes passing into a conical chamber at 

 top and bottom as shown in the diagram, 

 or it may take the form of a spiral pipe 

 coiled up in the vertical cylinder so as to be 

 surrounded by the cooling water. This 

 description will render intelligible some of 

 the pictures (Figs. 118 and 119) which 

 show several forms of still used in actual 

 practice. In the still used for the produc- 

 tion of otto of rose (Fig. 119) it will be 

 seen that with a view to economy of the 

 precious otto, the water from the receivers 

 is returned to the stills as it comes over. 



There are, however, other essential oils 

 which cannot be extracted from the flowers 

 or fruit containing them by a process of 

 distillation without injury to their delicacy. 

 In such cases as the violet, for example, 

 the flowers are macerated in hot lard, which 

 is afterwards pressed out retaining the per- 

 fume. The illustration (Fig. 122) which 

 shows this process in operation at one of the 

 factories at Grasse sufficiently explains itself. 

 In some factories the stirring by hand is 

 replaced by mechanical arrangements. 



According to another plan the scent may 

 FIG. 117. CONTINUOUS be extracted by immersing the flowers in 



EXTRACTIONAPPABATOB. 



wards be separated and distilled off leaving the essence behind. 

 The accompanying diagrammatic representation of the apparatus 

 employed in this process will render it easily understood. The 

 percolator B is a vessel in which the flowers can be placed so 

 that they are continuously exposed to a stream of the volatile 

 liquid, which is driven in vapour from the receiver A up the side 

 pipe G, and condensed again in the condenser C placed above. 

 The arrows show the direction which the vapour takes, after it 

 has been produced in the vessel A by the heat applied by means 

 of steam to the surrounding jacket or steam bath D. 



