casting in
an open mould. Copper ores are, however, very rarely found in a pure
state, and the small impurities of antimony, arsenic, &c., combine in
the smelting with the copper, and lend a hardness and ductibility
which would enable it to be cast in closed moulds.[8] The analyses of
Irish copper celts agree among themselves, and substantially with
those from other countries, the small quantities of tin, antimony,
arsenic, &c., which are found being due to impurities in the ore. The
celts may be taken to be of copper, and not of poor bronze.[9] The
earliest copper celts resemble the stone celts from which they are
derived; some of them are small. A development takes place throughout
the series, the celts becoming larger and the edges thinner as they
approach the bronze forms. No trace of a stop-ridge is ever found on
copper celts.

[7] Sir R. Kane, Industrial Resources of Ireland. Second edition, 1845,
p. 189.

[8] See analysis of a socketed celt of an alloy of copper and antimony
found at Elbing, West Prussia, Journal Anthropological Institute,
vol. xxxvi, p. 21.

[9] See paper "Irish Copper Celts," Journal Anthropological Institute,
vol. xxxi, p. 265, where the question is fully dealt with.

[Illustration: Fig. 1.--Copper Halberd, Birr find.]

The principal finds are as follows:--

1. Three copper celts, three copper awls, and a copper knife found,
in 1874, in a bog at Knocknague, Kilbannon, County Galway. Purchased
from the finder, Michael Rafferty, by the Royal Irish Academy. (Fig.
3.)

2. Three copper celts, a fragment of a fourth (butt-end), a copper
halberd, and a short blade of copper of somewhat similar form, found
in 1892, near Birr, King's County, formerly in the collection of Mr.
Robert Day, of Cork. (Fig. 2.)

3. Three copper celts found in 1868, when ploughing at Cullinagh,
near Beaufort, Killarney, County Kerry. (Day Collection.)

4. Two large and well-formed copper celts found together in street
excavations in Suffolk Street, Dublin, in May, 1857. (Ray
Collection.) (Fig. 4, nos. 1 and 7.)

[Illustration: Fig. 2.--Birr find.]

5. Two copper celts found together at Clontoo, near Kenmare, County
Kerry, in 1906. (Fig. 4, nos. 2 and 3.)

6. Six copper celts found together at Cappeen, County Cork.

The distribution, analyses, types, and finds show that the copper
celts represent a period when copper