Irish glass is generally very heavy, though there are exceptions to this rule, markedly in the blown specimens from about 1735 to 1750, which are extremely light. These pieces were never cut, but either engraved only or left perfectly plain. They can be distinguished from foreign pieces of similar weight, as they never show the little specks of sand in the metal peculiar to the latter. On the other hand, air-bubbles often appear in the Irish glass, which were caused by the faulty stirring of the molten metal. These are sometimes so minute that they appear like sand specks to the naked eye, and it is only possible definitely to identify them as bubbles by the use of a magnifying glass. COLOUR. All old Irish glass has a peculiar depth of tone, but the early glass of Cork, Waterford, and Dublin is especially distinguished in this quality. Its steel or grey-blue tone is unique. In this respect there is very little difference between the wares from the three places, as they are all characterised by the same mysterious grey colour (supposed to be caused by impure ingredients). It should be remembered that the factories in all three localities obtained their materials for glass-making from the same sources, and that the workmen employed in them frequently passed from one to another, so that, theoretically, the metal produced in the three towns should be practically identical. There are, however, tangible differences in at least a portion of the glass emanating from the various localities. Thus I have noticed that some Cork glass has a decided yellowish tinge which Waterford never has. On the other hand, Waterford glass is often distinguished by a peculiar cloudy bloom covering the metal, which can be rubbed off, but will assuredly return. This "bloom" must not be confused with the milkiness found in decanters, etc., which is caused by wine or water being allowed to remain in them for long periods. It is quite different: a soft bloom, exactly like that on grapes, the same colour, or even darker, than the glass, and often will be found forming a beautiful band of rainbow hue running round the piece it adorns. I do not know, for certain, the cause of this appearance, but it probably originates in some atmospheric action on the lead in the metal. It is only found on very early dark pieces, and its possession may be regarded not only as an additional charm of the piece so characterised but also as a proof of its authenticity. These pieces are most interesting, but are not always appreciated as they should be. Some time ago I parted with a magnificent Waterford bowl, beautifully toned in this manner, only to find a week later that it had been chemically polished clear and bright, leaving it with not a tithe of its pristine beauty.