4 ON Til P] CONSTRUCTION AXD USE OF 



inside with a mixture of beeswax and rosin (equal parts), At opposite ends of one 

 diameter two narrow pieces of wood, a a\ \ of an inch tliick, are cemented. They 

 are to keep the face of the mirror from the bottom of the vessel, and permit of a 

 rocking motion being given to the glass. Before using such a vessel, it is necessary 

 to touch any cracks that may have formed in the wax with a hot poker. A spirit 

 lamp causes bubbles and holes through to the tin. The vessel too must always, 

 especially if partly silvered, bo cleaned with nitric acid and water, and left filled 

 with cold Avater till needed. Listead of the above. India-rubber batlis lia\(' been 

 occasionally used. 



3d. In ordc^r to secure fine and liard deposits in the shortest time and with weak 

 solutions, it is desirable, though not necessary, to warm the glass slightly. This is 

 best done by putting it in a tub or otlun- suitably sized vessel, and pouring in water 

 enough to cover tlie glass. Then hot water is gradually stirred in, till the mixture 

 reaches 100^ F. It is also advantageous to place the vessels containing the in- 

 srredi(mts for tlie silverin-j: solution in the same bath for a short time. 



4th. On taking the glass out of the warm water, carry it to the silvering Aessel — 

 into A\hi<li an assistant has just previously poured the mixed silvering solution — 

 and iinniedinteh' ininierse it face downwards, di])ping in tiv^t on(> edgi" and tlicii 

 quickly letting down the other till the face is horizontal. The back of course is 

 not cov(n-ed A\ith the fluid. The same precautions are nec(>ssary to aAoid streaks 

 in silvering as in the case of putting a collodion i)lat(^ in the l)ath. Tlace the 

 Avliole a])|)aratus before a window. Ke(>p u]) a slow rocking motion oi' the glass, 

 and wiitcli for tlic ai)])earance of the l)nglit silver film. 'I'lie solution ([uickly turns 

 brown, and the silver soon after a[)pears, usually in from three to five minutes. 

 Leave the mirror in the licptid about six times as long. At the expiration of the 

 twenty minutes or half hour lift it out, and look through it at some very bright 

 object. If tlie object is scarcely visible, the silver surface must then l)e washed 

 with ])lenty of water, and set on edge on bil)idous paper to dry. If, on the con- 

 trary, it is too thin, ])ut it (|uickly back, and leave it initil thick enough. When 

 polished the silxcr ought, if held between the eye and the sun, to show Jiis disk 

 of a light l)hie tint. On coming out of tiie liath the metallic surface shoidd ha\c' 

 a rosv gohh'U color by refi(H-t(Hl light. 



Ath ^^'llen the mirror is thoroughly dry, and no dro])s of Avater remain about 

 the edges, hiy it upon its back on a thoroughly dusted table. Take a piece of the 

 softest thin buckskin, and stiitt' it loosely with cotton to make a rubber. Avoid 

 using the vilixv ])ieces of a skin, as they are always hard and contain nodules of 

 lime. 



(to gently over the Avhole silver surflice Avith this ndiber in circular strokes, 

 in order to commence the remoA'al of the rosy golden film, and to condense the 

 silver. Then having put some very fine rouge on a piece of buckskin laid flat on 

 the table, impregnate the rubber Avith it, The best stroke for polishing is a motion 

 in small circles, at times going gradually round on the mirror, at times across on 

 the Aarious chords (Fig. 2). At the end of an hour of continuous gentle rubbing, 

 Avith occasional touches on the flat rouged skin, the surface Avill be polished so as 

 to be perfectly black in oblique positions, and, Avith even moderate care, scratchless. 



