VOL. XX.J PHILOSOPHICAL TRANSACTIONS. 317 



Some Philosophical Experiments, communicated by the Right Hon. Sir Robert 

 Southivell. V. P. R. S. N° 245, p. 363. 



1. To make the Globe Looking-Glass. — Take quicksilver, marcasite of silver, 

 of each 3 ounces ; tin and lead, each half an ounce ; these first two throw on 

 the marcasite, and last of all the quicksilver; stir them well together; but 

 they must be taken from the fire, and almost cool before the quicksilver be 

 added ; let your glass be well warmed, then pour out the mixture, and roll it 

 from side to side. 



Note, this will do also when cold ; though it is best when the glass is 

 heated, and very dry. 



Note also, That if at the glass-house, your ball be of yellow glass, then all 

 will shine like gold. 



2. To paint Glass in Marble Colours. — First grind well upon a stone some 

 minium for red. 2. Radix curcumse, or rather cerussa citrina for yellow. 

 3. Smalt for blue. 4. Verdigris for green. 5. Cerusse, or chalk, for white. 

 Which being all separately wrought in oil, take a brush of hog's hair, dipped 

 in any of the said colours, and it will, being rolled in your hand, scatter the 

 same upon the glass ; then with your pencil work them together as you think 

 fit ; and lastly, fling a little mead among them, which covers all. 



3. The Magic Lantern. — In order to give variety of colours to these lanterns, 

 which are generally made to represent dark figures, take oil of spike, and mix 

 in it the several colours, with which you will have your glass stained, paint 

 them finely on ; they will dry presently, and penetrate any glass. 



4. Phosphorus Metallorum. — Take lapis smaragdi mineralis, and beat it into 

 a very fine powder. If you strew this very fine on any metal, and in any 

 figure, and set the plate on hot coals, you will in a short time perceive a light 

 shine which will last as long as you continue the hot coals ; and if you 

 beat out the fire, it may do again for once or twice ; but then the virtue 

 will fade.* 



On some Mineral Waters at Eglingham in Northumberland. By Dr. Cay, of 



Newcastle. N°245, p. 365. 



A mineral water was sent me by Mr, Duncan, a skilful surgeon in Alnwick, 

 which he desired me to examine, and give him an account of. Accordingly I 



* Many other spars, besides this, become phosphorescent under similar treatment. See Mr. 

 Tho. Wedgewood's experiments on the production of hght from different bodies by heat and attrition 

 in the 82d vol. of the Phil. Trans. 



