For the destillatio per descensum on a small scale, glass vessels heated from the side (fig. 30) were also employed, and for some easily distilled substances even the heat of the sun (destillatio sol is) (fig. 31) was used. At present the preparation of empyreumatic oils as well as of the finer tars is effected in cast iron or earthenware cylinders.

Titles, such as de furnacibus construendis, as well as illustrations of some of the older treatises, already enumerated, reveal that no little attention was given during the middle ages to the construction of distilling furnaces. Abundant evidence thereof is found in the 16. century treatises on distillation. Besides the distilling apparatus most generally used at that time, and reproduced in figs. 11, 12, 15, 18, 22, 24, 25 and 26, the socalled faule Heinz or Athanor (fromIV History Of The Methods Of Distillation And Of D 65 imperishable), called furmis Acediae by Ulstadt (fig. 32), was much in favor and was used to a great extent for the distillation of waters and oils. Above a common fireplace were placed three or more distilling retorts with Rosenhuthelm (p. 211, fig. 22). The fireplace ended in a central iron, copper or earthenware pipe, the opening of which could be closed by a cover. By means of slides at the sides of the fireplace the heat could be conducted under any one of the stills or retorts as desired, and the distillation was thus regulated.

Fig. 30.

Fig. 30.

For the distillation of large quantities in a large number of individual retorts or stills, larger cupil furnaces after the manner of the so-called "galley furnaces" appear also to have been in use. The illustrations and descriptions of these in some of the treatises on distillation of the 16. century represent no doubt more the possibility than the realization of perfection. The illustrations of these furnaces were transferred from one distilling book to another, but the furnaces themselves probably have not been generally used in practice. Among others they are thoroughly described in the text and reproduced by illustrations in the works of Matthiolus and of Lonicer previously mentioned. They are built either in the shape of a terrace (fig. 33), or of a bee hive (fig. 34). Matthiolus describes one of the latter type, in which the retorts are placed between the tiles, and its mode of operation in the following words:1)

Fig. 31.

Fig. 31.

Fig. 32.

Fig. 32.

Fig. 33.

Fig. 33.

Ultima hac fornace utuntur Veneti ac Neapolitanl, qui vitreis alem-bicis abundant. In aqua una tantum die et node, sicco ignis calore, eliciunt quae ultra centum libras. Fornax rotunda est, ut ex imagine hic appicta apparet, fornacibus, quae in Genuanorum visuntur vaporariis, omnino similis. Contmet haec circumcirca numerosa fictilia, intrinsecus vitro incrustata, urinalis forman referentia et diligente sane artificio argillaceo luto aggluti-nata, quibus singulis per rotum fornacis ambitum singuli adduntur vitrei alembici, e quorum vertice ex globulo ad hoc parato, recipientia crassius-culo tuniculo ad alligata, pendent. Calefit haec fornax eodem modo, quo Germanicorum vaporariorum fornacis. Atquedum ignis vehemens est, vacua relinquunt vasa, donec parumper remittatur, ne violente calore plantae et flores exurantur. Tunc itaque plures ministri, qui hoc tantum artificio aluntur, obstructo undique fornacis ostio, ne conclusus expiret calor, herbas fictilibus injiciunt, et simul vitreos applicant alembicos. Atque in hunc modum copiosas eliciunt aquas et olea, quae longe meliores habentur, quam quae plumbeis conficiuntur instrumentis, quod nullam metallorum contrahunt infectionem.

Although the compilers of the distilling books of the 16. century have successively followed the pioneer work of Brunschwig, especially in regard to illustrations, their writings nevertheless quite often show considerable differences in views, practical skill, and experience, and also in the originality of their knowledge and ability. With but little public intercourse these secluded workers and writers toiled mostly far from one another, each in his own sphere and manner, often with but a slight knowledge of the older writings and of the work of his contemporaries. With regard to the manner of distillation of the aromatic waters and oils, this is shown in an unmistakable manner in works compiled in the course of the first half of the 16. century by Philipp Ulstad, Walter Ryff, Adam Lonicer, Valerius Cordus, and Conrad Gesner. All of these were mainly based on the writings of Hieronymus Brunschwig. Their views, however, as to the nature of distillation itself and of the distilling methods and apparatus are neither in accord with those of Brunschwig, nor with those of their contemporaries.

1) Petri Andreae Matthioli Opera quae extant omnia. Supplementum: De ratione destillandi aquas ex omnibus plantis: et quomodo genuini odores in ipsis aquis conservari possint. Basiliae 1565. p. 5.

How little personal skill, practical experience and familiarity with the literature on the subject may be found in the writings and methods of working of the most prominent experimenters of that time becomes apparent e. g. from the construction of and preference for the distilling vessels employed. Thus for instance, Valerius Cordus,1) profound in theoretical science, but ignoring the rationally constructed distilling apparatus then well known, used and recommended ein Ko/b mit einem angeschmelztem Helm (fig. 35) as an efficient apparatus meeting all the requirements of the art. At the same time Conrad Gesner,1) his contemporary, used for the same purpose a distilling furnace (fig. 36), which had long been in use.

Fig. 34.

Fig. 34.

Fig. 35.

Fig. 35.

Fig. 36.

Fig. 36.