wording. Franz Welz in Klostergrab registered a “process for making red-colored glass” 
(Priv. No. G. 42/2560, Grant 5.10.1892, Priority 14.1.0.1891; Privileges Catalogue 1896, 
no . 134444, p. 1078, also 1898, No. 14729, pp. 1189 and 1899, No. 11763, p. 967). In this 
connection the notes made by Alois Franz Welz on “The History of Coloring Glass with Se- 
lenium" are especially important (typescript 1942) (s. pp. 226-227). 
“The object of the process presented here is the production of red-colored glass, which es- 
sentially consists of adding selenium to the glass melt. This additive has the effect that the 
glass melt taken from this pot for use gets a reddish to red color, to which I have given the 
name Creme rose. 
The amount of additive needed, depends for one thing on the formula for the glass melt, 
which as it is known, depends primarily upon whether softer or harder glass is intended, 
and for another, according to the depth of the color shade desired. The accompanying sam 
ple shows a glass cone, the color of which has been achieved by adding selenium to the 
batch. 
This cone was worked from the pot which held glass melt made from 
75 parts in weight of sand, 
7 1 / 2 " slaked lime, 
2 " soda, 
15 " potash, 
4 " potassium nitrate 
4 " sodium nitrate, 
5 " borax 
0.375 " selenium 
New and also an item in the privilege is: a process for making red-colored glass, consisting 
in adding selenium to the glass batch.” 
The privilege held by Dr. Alfons Spitzer, Vienna, for “Using selenious or selenic salts to color 
glass rose-red” (Priv. No. O. 43/3572, Grant 10.9.1893, Priority 18.2.1893) was passed on 
to Wilhelm Kralik Sohn in Eleonorenhain (Privilegien Catalogue 1896, No. 11961, p. 959): 
“To color glass melt, sodium selenite or potassium selenite or calcium selenite or corre- 
sponding selenides or other selenious and selenic compounds are added to the melt in a 
greater or lesser quantity depending on the intensity of the color desired. It is necessary to 
wait until all the salts added are completely dissolved in the melt and at the same time 
everything must be stirred well. At this point suitable reducing agents such as arsenious 
acid, sodium arsenite, potassium arsenite, sodium Sulfite, in short, whatever reducing 
agents in amounts that correspond to the quantity of selenium compounds used, are added 
and stirred well in order to achieve a complete rose-red coloration of the glass by means of 
the now precipitated selenium.” 
A “Process for decolorizing glass, or coloring glass rose-red” (Privilege Catalogue 1898, 
No. 13118, p. 1061; Grant 16.2.1898, Priority 15.1.1898, Priv.No. G 48/1111) goes back to 
Dr. A. Spitzer and L. Wilhelm, Vienna. 
Schnurpfeil (1906) lists, “gold, copper, selenium and manganese, also iron oxide” for color 
ing glass red. His formulas 80 - 83 contain selenium and result in the colors “rose-red, red, 
rose or roses, and pink” (s. p. 220) along with the color aurora (s. p. 222). In his publication 
dated 1923, Schnurpfeil also lists “pink colored glass (salmon colored)” (s. p. 224). In addi- 
tion, the same author recommends formulas for selenium ruby glass and sulfur ruby glass 
(s. p. 225). Ludwig Springer (1937) mentions “a pink to yellowish red coloration,” achieved 
by using selenium compounds (s. p. 225). 
140