88 The Irish Naturalist* Aprils 



its uneven fractured surface often shows a black resinous lustre. 

 The specific gravity of this layer, as taken by a Walker's 

 balance, was 2*50, the specific gravity of the ** cinder " being 

 2 •67. On being sectioned and examined, it wafi found to be a 

 typical basalt in a fairly fresh condition, the felspars and 

 olivine being only slightly altered, covered by a crust of iron 

 oxide. Nevertheless there is au abundance of small groups 

 of rhombic zeolites, and the magnetite has been hydrated and 

 changed to limonite. 



The crust, being the more interesting part, I examined 

 chemicall)^ and found it to contain iron oxide, manganese, 

 magnesium, calcium, carbonic acid, phosphoric acid, and 

 water, w^hich are the usual constituents of bog iron ore. 



Another portion was taken with a view to the estimation 

 of the iron present. After being crushed, when it had the 

 appearance of cocoa, it was dried at 100° C, weighed, and then 

 treated with warm hydrochloric acid for some time, until all 

 the iron was dissolved. The insoluble residue, consisting 

 mainly of silica, was carefully washed, and the washings added 

 to the dissolved iron and made up to 500 c.c. with distilled 

 water. The ferric chloride was then reduced to the ferrous 

 state with stannous chloride and titrated with a standard 

 solution of potassium permanganate. Several determinations 

 were made, the result being that I found the percentage of 

 iron present to be 38'89. The insoluble rCvSidue was dried at 

 100*^ C. and weighed, the percentage being 1890. 



If the iron be calculated as limonite (2 FeoO.j, 3H2O) the 

 percentage is 6493, which with the insoluble matter brings 

 the total to 83*83 per cent. The rest is made up of manganese 

 and phosphoric acid, of which there is a fair amount, and 

 much smaller quantities of calcium and magnesium carbonates. 



When Mr. Welch's ore was examined, I found it to be very 

 variable. It consists of small, rounded masses, some spheroidal 

 with concentric structure, others flattened and disc-like. 

 Some, however, on being broken open, showed that they were 

 small rounded and sub-angular pieces of basalt, with an ex- 

 ceedingly thin layer of ore on the outside which gave them 

 the same appearance as the rest of the masses. All apparently 

 have a nucleus of basal t\ and specimens can be found show- 



^ One specimen seemed to the naked eye to have as nucleus a tiny frag- 

 ment of mica schist. 



