280 SILVERING* 



proper consistence ; then immediately, before it 

 grows too stiff, lay the glass, with its convex 

 side downward, in the middle of the plate, and 

 press it until it lies quite close to the plaster ; in 

 which situation let it remain until the plaster be- 

 comes quite dry. After which, work a groove with 

 your finger, round the outside of the glass, in 

 order to let the superfluous mercury rest upon it ; 

 then cut the tinfoil to a proper size, and press it 

 with the glass into the plaster-mould, in order 

 to make it lie close ; after which, cover it with the 

 mercury, and, without a paper (as directed for sil- 

 vering plain mirrors), slide it over the silvered foil ; 

 then place a weight on it, and let it stand two or 

 three days, rising it by degrees, that the mercury 

 may drip off gradually. 



After this method common window-glass, &c. 

 may be silvered. 



To lay Paper Prints on the Inside of Glass Globes. 



First, cut off all the white part of your impres- 

 sion, so that nothing appear but the print ; then 

 prepare some strong gum arabic water, or size, 

 with which you must brush over the face side ; 

 after which put it into the globe, and with a long 

 small stick, on which a camePs-hair pencil is fixed, 

 stick it even on ; and by this method you may put 

 what number of prints you please into the globe. 

 Let them dry about twelve hours; then pour some 

 prepared plaster of Paris, either white or tinged, 

 whatsoever colour you please, and turn the globe 

 easily about, so that every part be covered ; pour 

 put the superfluous plaster, and it is finished. 



