Beginning about the middle of the past century the earlier, simple apparatus took on a different shape in the factories of this larger industry of the volatile oils. The original small distilling apparatus were replaced by larger and more rationally constructed ones which not only effected a better exhaustion of the vegetable matter and thus increased the yield, but also produced oils of a better and purer quality.

The apparatus commonly used in the factories about the middle of the present century, were the stills arranged for the so-called water-distillation, and others for the so-called dry steam-distillation.

The first type of still (fig. 44) is a simply constructed apparatus for the distillation of plant material in water, as well as for the rectification of crude oils by steam. The still is heated by means of steam admitted under pressure through the holes of a ring d at the bottom, or by allowing the steam to escape directly into the lower double walled jacket B. The aqueous distillate constantly flows back into the still through the tube F. In the distillation with dry steam (fig. 45), the still is filled with the plant material without the addition of water and distilled with steam passing through the material from the bottom upwards. These or similarly constructed steam distilling apparatus are employed even at the present time for the distillation of some of the oils, only, in place of the spiral, a tube condenser is used.

With the introduction of these apparatus during the middle of the past century the volatile oil industry had taken its position as a branch of the rapidly developing chemical industry at large with southern France and central Germany as the principal centers of production. Owing to the remarkable development of the entire perfume industry during the second half of the past century, the consumption and commerce of the volatile oils assumed entirely unanticipated proportions and importance. Scientific and technical attainment, commercial interests and business competition brought about numerous changes in rapid succession. More rational methods of distillation were devised, large apparatus for the distillation of enormous quantities were constructed. Some of the largest have a capacity of from 30000 to 60 000 liters.

Fig. 44.

Fig. 44.

The evolution of the modern distilling apparatus as applied to the distillation of volatile oils, like that of the theory and art of distillation in general, is replete with historical interest.

On the following pages will be found a number of illustrations of some of the modern stills used in the largest German factory. Looking backward it might seem as though there were no connection between the modern giant stills and their prototypes. Yet every one of them is but a link in the long chain of develop- ment of the art of distillation. That the process of evolution has been exceedingly rapid during the past ten years does not affect the truth of this statement. Almost every one of these pieces of apparatus has been newly created out of the ruins of its immediate predecessor.

Fig. 45.

Fig. 45.

In modern chemical industry Germany unquestionably ranks first. Of the various branches of this industry that of the manufacture of volatile oils and synthetic aromatics has acquired an importance previously unexpected and with it a correspondingly influential position.

Fig. 46. Modern distilling and rectifying apparatus.

Fig. 46. Modern distilling and rectifying apparatus.

Fig. 47. Distilling and rectifying apparatus.

Fig. 47. Distilling and rectifying apparatus.

Fig. 48. Distilling apparatus for water distillation.

Fig. 48. Distilling apparatus for water distillation.

Fig. 49. Distilling apparatus of 30000 liter capacity.

Fig. 49. Distilling apparatus of 30000 liter capacity.

Fig. 50. Distilling apparatus for spices.

Fig. 50. Distilling apparatus for spices.

Fig. 51. Giant distilling apparatus of 60000 liter capacity.

Fig. 51. Giant distilling apparatus of 60000 liter capacity.

Distillation of rose oil

Fig. 52. Distillation of rose oil.

Modern distilling apparatus

Fig. 53. Modern distilling apparatus.