44 PHILOSOPHICAL TRANSACTIONS. [aNNO 1 665^. 



glass mil be equal to „ ~ - from which subducting B (the given focus of 



the object-glass) there remains - ; and if this sum be supposed equal to 



C, we shall easily know, by the preceding rule, the focus of the second 

 glass. 



j4 Way of preparing a Liquor that shall sink into and colour the ivhole 

 Body of Marble ; causing a Picture, drawn on a Surface, to appear 

 also in the inmost Parts of the Stone. By A. Kircher. N" 7, pl^5. 



The colours are thus prepared : Take of aqua fortis and aqua regia, two 

 ounces each; of sal ammoniac one ounce; of the best spirit of wine, two drams; 

 as much gold as can be had for four shillings and six pence ; and of pure silver, 

 two drams. These materials being provided, let the silver, when calcined, be 

 put into a vial ; and having poured upon it the two ounces of aqua fortis, let it 

 evaporate, and you will have a water yielding first a blue colour, and afterwards 

 a black. Likewise put the gold, when calcined, into a vial, and having poured 

 the aqua regia upon it, set it by to evaporate : then pour the spirit of wine 

 upon the sal ammoniac, leaving it also till it be evaporated ; and you will have a 

 golden coloured water^ which will afford divers colours. After this manner 

 you may extract many tinctures of colours out of other metals. This done, 

 you may, by means of these two waters, paint what picture you please on white 

 marble of the softer kind, renewing the figure every day for several days with 

 some fresh superadded liquor ; and you will find in time, that the picture has 

 penetrated the whole solidity of the stone, so that cutting it into as many parts 

 as you will, it will always represent to you the same figure on both sides. 



But whether this experiment will succeed, or not, it is certain that Mr. Bird, 

 a stone-cutter in Oxford, has many years ago found out a way of doing the 

 same thing, and has practised it for many years. That is, he can apply a co- 

 lour to the outside of polished marble, that shall sink a considerable depth into 

 the body of the stone, and there represent the same figures as those on the out- 

 side, deeper or shallower as he continues the application a longer or shorter 

 time. Several pieces of which are to be seen in Oxford, London, and else- 

 where. And some of them being shown to his majesty, they were broken in 

 his presence, and found to answer expectation. 



China JVares made in Europe. N° 7j p- 127- 



Notice was lately given by a Parisian to a friend in London, that he had been 

 informed that Signior Septalio, a canon in Milan, had the secret of making as 



