yes I see what you mean -according to the Count, for it to be classed as opaline i.e opal 'like', the glass needs to have opalescent properties. And in fact he states a method of producing opaline glass on page 66 as follows:
' Opaline glass is produced by mingling in the common metal of white glass, a portion of calcined bones, which gives a blue shade without impairing the transparency.' - Source: volume 26 - American Journal of Science & Arts in July 1834: Ch VII On the colour of the air and deep Waters and on some other analgous fugitive colours, COUNT XAVIER DE MAISTRE - page 66
I have attached a picture of my Salviati ewer which I believe demonstrates his sentence above. I would class it as opalescent glass not opaline glass though.
I think this poses a question mark over what is often now termed opaline glass?
Harold Newman has a different description of opaline glass - this is a quote from an article online that was put on the Beerstein website:
Source: this is a link to The Beerstein site on the net (
http://www.beerstein.net/articles/bsj-1b.htm ) that has reproduced a list of glass terms under the heading ‘ Glass Glossary , Terminology for the Glass Collector* by Ron Fox’, citing as reference sources An Illustrated Dictionary of Glass, by Harold Newman and with permission cited as *Reprinted from The Beer Stein Journal, August 1994,by permission from Gary Kirsner Auctions.
Within that list are the following terms and definitions:
‘ Bone ash – ashes of bones used as flux in the glass-making process that produces Opaline glass.’
‘Opaline – a dense translucent glass that derives its diffused nature from the addition of bone ash, and is colored using metallic oxides, usually in pastel hues.’
Or perhaps I've just been identifying the pieces incorrectly? .... along with many other people.
I don't agree with the definitions of opaline glass in Wikipedia or in Britannica though. According to various sources I have found (Hajdamach British Glass 1800-1914, Dan Klein, The History of Glass) opaline glass was produced in France, Bohemia and Great Britain in the 19thc. (will provide sources in my post below in the thread)
And if you use the source I gave above, then opaline glass was produced in Venice in the C17th - Sandra Davison, Conservation and Restoration of Glass).
Felice Mehlman adds America to that list and has a different definition of opaline glass:
Source - Felice Mehlman : The Illustrated Guide to Glass - Page 216 under the heading Opaline
‘Opaline is a semi-opaque translucent glass, often of “milk and water” appearance or coloured, produced in France 1825-1870 at Baccarat (where the term opalin was first used c 1823), Saint-Louis, Le Creusot, Choisy-le-Roi, Bercy and other factories. Early wares – vases, carafes and boxes, were of elegant form and proportion, frequently ormolu-mounted and of subtle shades. After about 1835, surfaces were sometimes enamelled and/or gilded, and as production increased to meet demand the range of opaline extended to include variety of domestic wares. Special colours were: gorge de pigeon (“pigeon’s neck” : translucent mauve); bulles de savon (soap bubbles: delicate rainbow hues); yellow, turquoise and violet. White, bright greens and blues were more common. In England, opaline was manufactured in the 1840s and 1850s by Richardson of Stourbridge (painted and gilded with classical scenes, flowers, or with trailed decoration such as coiled serpants), George Bacchus of Birmingham (transfer- printed designs for cheaper wares), J.F. Christy and Rice Harris of the Islington Glass Co.; and in the USA after c1830 by the Boston and Sandwich Glass Co. Since c.1932 opaline manufacture has continued in Venice.’