BOHEMIAN GLASS. 347 



the resultant ashes afforded the necessary potash. The Bohemian 

 crystal serves in art as the type of the most perfect glass, and is un- 

 questionably recognized as one of the superior kinds, rivaling in trans- 

 parency and clear whiteness rock-crystal itself. Pure specimens of it, 

 free from blisters, grains, and specks, have a peculiarly attractive 

 look, even, in their simplest forms. It is, moreover, by reason of its 

 tenacity, its constancy of luster, hardness, and difficult fusibility, emi- 

 nently adapted to artistic molding and ornamentation. 



The heating of the furnace with wood only, from which a compara- 

 tively small quantity of ashes was produced, and they entering into 

 the composition of the glass, contributed no little to the attainment of 

 the highest perfection. While the glass-houses were at first built 

 where they might be made a means of utilizing the superfluous wood, 

 they have now to contend against a continually rising price of wood 

 and increasing difficulty in procuring it. t Some factories, like the 

 Josephinenhtitte of Count Schaffgotsch, and that of Count Harrach at 

 Neuwelt, have the extensive forests of their owners to rely upon, while 

 the much more important establishment of Joseph Riedel in Polaun is 

 looking forward to direct railroad connection with the lower Silesian 

 coal-mines or the Bohemian brown coal. 



While formerly only the best, finely-split, well-seasoned trunk- 

 wood could be depended upon to heat the furnaces to the needed 

 temperature, the required degree is now obtained from limbs, knots, 

 roots, and even green wood, by distilling the gas from them in an 

 imperfectly ventilated regenerator, and burning it with the aid of 

 previously heated air. By this means is obtained a clear, excessively 

 hot flame, by which the most infusible glass is made as fluid as water, 

 and of a very high state of purity. Many experiments will be neces- 

 sary before such excellence can be obtained with coal-gas ; and, in any 

 event, a previous washing of the gas will be required to clear it from 

 tar and ashes. The form of the furnace, the manner of introducing, 

 purifying, and tempering the glass, the processes of bringing it into 

 shape, and the shaping tools, do not vary essentially from those of 

 the old ways ; except that complicated figures engraved in iron and 

 brass molds are now applied, the complete transference of which to 

 the glass necessitates the use of air under high pressure. This is fur- 

 nished by means of a hand compression-pump, so arranged in connec- 

 tion with the other parts of the apparatus that the manipulator can 

 bring it to bear upon the melted glass at the precise moment when it 

 must be brought into the closest contact with the engraved pattern. 

 Other pieces, of a massive character, such as lenses and ring-segments 

 for lighthouse-lanterns, which are now made on a large scale at Po- 

 laun, are formed by subjecting the material to a light pressure between 

 an upper and a lower mold. They are then finished and polished after 

 they have cooled. 



The after-decoration of the glass is various, and subject to the fre- 



