are either transparent or opaque . . comments Stephan Edler von Keess already in 1823 (Keess 
2/1823, p. 889). 
“The opaque colored glass pastes are very numerous and were made to perfection only in Venice, 
where they are presently still being produced with exceptional beauty and made into cut stones, 
beakers, small bottles, beads, glasses, bowls, mortars, candle sticks, walking cane knobs, han 
dles for sabers, daggers, knives and forks, mouthpieces for pipes, etc. These pastes are given 
different names, after stones, i. e., aventurine, lapis lazuli, Chrysoprase, turquoise, Obsidian, 
jasper, agate, etc. .. .” (Keess-Blumenbach, 1830, p. 682). 
We find the term “glass composition” frequently in the inventory of the Technical University. Since 
it is always connected with the year 1837, the relevant selections are listed here. 
From the “Imperial Mineral Cabinet’' came “A piece of purpurine, a glass composition, which is 
made into boxes, stones for rings and such." (TH 32712). There is also, albeit of unknown prove- 
nance, “A collection of all the shades of colored glass compositions /: enamel colors :/ which are 
used for enameling on gold and silver, along with melted down test pieces; on two tablets placed 
in a box with compartments” (TH 32740), and another interesting group is a “Survey of the work 
of a gemstone cutter with all the categories of cuts” (TH 14806), to which “1-17 composition 
stones /: imitations of all the precious stones:/ on little pedestals” also belong (the rest of the 
work consisted of semi-precious stones, rings, beads and three kinds of garnets, etc.). 
The most imposing, however, was the Ferdinand Unger Company from Liebenau in Bohemia, rep- 
resented with the most diverse samples (TH 32835, 32852). The most noteworthy among them are 
the “Compositions and glass fluxes in rough pieces in 2 cartons” (TH 32837, 32838) and the 
“numerous items produced by pressure from the above mentioned compositions; in 2 cartons” 
(TH 32839, 32840) (most of these were beads, rings, little bottles, chandelier stones, etc., which 
cannot be described in detail here). 
The glass fom the Cabinet of Factory Products, which was subjected to a vicissitudinous fate, are 
sometimes found today in different Containers than those in which they were originally placed. 
For that reason, mistakes of identity are not rare. This makes extreme care in identifying the raw 
material all the more important. 
In the Cabinet of Factory Products there were a number of “glass compositions," and gemstones 
produced from them. In the course of time the descriptions that belonged to them were entirely 
or partially lost in transport or for other reasons. Therefore, Identification can only be undertaken 
with the utmost caution. This also applies to the attribution of the little cartons with labels which 
contain valuable Information on the ingredients of “compositions.” 
The label on a kind of wooden drawer in which a series of colored “lumps” of glass were found, 
bears the number 11655 and the wording, “From Blaschka and / Sons in Liebenau / in the Bun- 
zlauer Di= / strict, Bohemia, 1835.” 
Under the number 11655 in the inventory of the Technical University, “53 pieces of raw glass com 
position, of the type used for imitation gemstones. In a wooden box” are listed. The origin is given 
as “Blaschka, Liebenau, Bohemia." (1837 inventoried). 
The next number (11656) in the inventory mentions “126 pieces of large cut composition gem 
stones in various shapes and colors, corresponding to the glass compositions under 11655. In a 
drawer belonging to the previous box.” Origin and year of inventory are identical with those under 
the number 11655. 
It is highly probable that these “glass compositions” (glass pastes) are identical to those shown 
by “Blaschka and Sons in Liebenau, Bohemia, Bunzlauer District (Exp. no. 493)” at the Vienna Ex 
position of 1835: “. . . a complete assortment of glass compositions in raw pieces; a very exten 
sive collection of gemstones (imitation precious stones) in different sizes, made from these glass 
compositions . . .” (Vienna, 1835; Report, pp. 245, 246). 
A selection of “raw glass compositions” stored today in the Technical Museum covers shades 
from the palest yellow through opaque yellow hues to deep, dark red (ills. 10-12), from cobalt 
blue to aquamarine (ills. 13, 14), from “turquoise” and Chrysoprase (ills. 15, 16) (and the cut 
stones made from them) to different shades of opaque lumps of glass (ill. 17). When the irregulär 
lumps show the dark blue lightening up to the palest hint of blue, what we are seeing are the va 
rious intensities of coloration (ill. 13) as a result of the corresponding thickness of the transparent 
glass. In the deep brilliant red the incandescant red heat of the molten glass appears to be held 
fast (ill. 12). 
Little cards with hand-written descriptions give a good insight into the makeup and coloration of 
the “compositions” (probably those from the Blaschka Company). Here we can differentiate be- 
tween two groups: colored transparent and colored opaque or translucent glasses (recognizable 
by the formulation, “Saturation through phosphoric Urne"). 
The transparent compositions (glass pastes) included: “Coloration through gold" (32697, 32698, 
32699); “Black coloration through manganese.” (32700, 32701, 32702); “Coloration through gold 
(not yet completely warmed-in).” (32705); “Coloration through copper; with the addition of ura- 
262