478 



Popular Science Monthly 



Diagram of a Drill About 3 Inches in Length 

 for Drilling Plate Glass 



Making a Plate-Glass Drill 



THE accompanying diagram shows a 

 drill about 3 ins. in length for tlu- 

 drilling of plate-glass. It can be made 

 from an old corner-file. It allows for the 

 drilling of any size hole, which depends 

 on the size of file and the length and size 

 of taper. 



The piece of file is ground down along 

 its side on a taper until a point concen- 

 tric with sides of the file is obtained. The 

 point should then be cut off obliquely, as 

 shown in the illustration. It is then 

 ready for use. Drills of this kind can be 

 used for many years with satisfactory 

 results. — John Havkkost. 



Coloring of Copper 



COPPER and bra.ss lend themselves 

 readily to a coloring process and 

 may be worked to all shades and hues 

 imaginable by merely oxidizing the 

 surface of the metal. Make a paste of 

 iron oxide and graphite with wood 

 alcohol or with plain water, and apply 

 this to the article, which is then hcateil 

 in an oven or over a suitable gas flame. 

 It is belter to use alcohol as it dries out 

 much quicker. The color obtained will 

 depend on the amount of iron oxide 

 mi.xed with the graphite and the length 

 of time that the heat was maintainetl. 

 The more oxide in the coating the 

 darker the shade will be. Tiie remains 

 of the coating shfuild I)e remoxed with 

 a brush or cloth moistened in alcohol, 

 and when the surface has become quite 

 clean the color should be ])rotected by 

 ap|)l\ ing varnish, la((|iuT or pure \\ax, 

 wliicli may be laid on with a brush 

 while the copper is heated. 



Some brown colors are obtainefl by 



using a mixture of verdigris, sal ammoni- 

 ac and \inegar, using two or three times 

 as much verdigris and sal ammoniac as 

 vinegar. The color or shade can be 

 rendered much darker by adding some 

 blue \itriol to the s<^jlution. A red 

 brown may be given b\' using a vinegar 

 paste, containing equal parts of verdigris 

 and cinnabar, together with two and 

 one-half times as much each of sal 

 ammoniac and alum. The heat treat- 

 ment is the same as for the other 

 coatings. A wide range of colors 

 comprising shades from blue-black to 

 blue-gray may be given to the copper 

 by dipjiing it in a hot "liver of sulphur" 

 solution, then washing thoroughly, re- 

 dipping, or scratch-ltrushing, and again 

 dipping and washing if desired. 



A Handy Spacing Scheme 



THE drawing illustrates a handy 

 .scheme for drawing parallel lines 

 spaced accurately at equal distances. 



Take a strip of ruled paper and fasten 

 it where\-er you choose on the drawing- 

 board. The ruled lines on the strip are 

 used for guides cither for the T-square 

 or for triangles. The strip may be 

 fastened vertically on the board, hori- 

 zontally, or at any angle. 



In case of absence of ruled quadrangle 

 paper, advertisement borders do very 

 well. I have used the "spaced variety" 

 of advertisement border successfully 

 many times. It will be found in various 

 spacings. — N. G. Ne.vr. 



Ruled Lines on the Strip Are Used for 

 Guides for T-squarc or Triangles 



