ti Scientific Notices-^Mineralogi/. fJuLY^ 



Another sample *.*.*•... 70 grains 



Two other indigoa . •♦,."• 4 i i •'.'.. 60 



Two other samples 60 



Another sample 40 



Another sample ^ 30 or 35 



Mr. Dalton is of opinion that to destroy indigo by oxymuriatic 

 acid, twice the quantity of oxygen is necessary that is required 

 %o revive it from the lime solution. See Manchester Memoirs, 

 New Series, vol. iv. p. 437, 438, 439. — (Edin. Jour, of Science.) 



Mineralogy. 



3. On the Geological Situation of the Beryl ^ discovered in the 

 Count!/ of Down* By Sir Charles Giesecke. 



This substance, which had been discovered some years ago 

 in the county of Wicklow, in Ireland, in a coarse granular gra- 

 nite, has also been found lately in the county of Down, between 

 Kilkeele and Newcastle, fifteen miles from Rostrevor, where it 

 occurs in a coarse granular granite, which is more or less decom- 

 posed. It is very remarkable that this granite bears an extraor- 

 dinary resemblance to the granite of Adontschelon, in Dauria, 

 in which the beryls are found there. It is of a perfect crystal- 

 line structure, all its constituent parts presenting more or less 

 perfect crystals. Those of rock crystal are the most distinct, 

 and are generally of a brown colour, of different shades. The 

 felspar is generally of a milk-white and yellowish-white, seldom 

 of an ochre-yellow colour. Mica occurs only in small silver- 

 white and greyish-white particles, and is wanting entirely in 

 some parts of the rocks, particularly where the beryl is found in 

 veins. The beryl itself occurs in apart of the Morne mountains, 

 about three miles from the shore, partly in small veins, partly 

 irregularly imbedded in the rock, and partly in detached and 

 broken crystals in the sand of decomposed granite, and in the 

 overlaying bog land. 



Then follows a description of the beryl and its crystalline 

 forms, which our limits oblige us to quote very briefly. Their 

 colour is principally blue, of various shades — sometimes green, 

 and pale wine-yellow. Some of the crystals present, on the 

 end of their lateral edges, towards the terminating edges, per- 

 fect triangular delineations of a pearl-white colour, which have 

 the appearance of a previous truncation of the terminating 

 angles, filled up again by some process of nature. The largest 

 crystals were from four to five inches long, and one inch in 

 diameter. The form of the crystals is that of a six-sided prism, 

 perfect, and variously truncated. . t - 



The rock crystal which accompanies the'beryl' is- of different 

 shades of brown, seldom of a greyish white, and yellowish-white 

 colour. 



