M. TECHNOLOGY. 531 



viously thoroughly dried and warmed, is coated once or 

 twice with a stain composed of one part, by weight, of ex- 

 tract of walnut-peel, dissolved in six parts of soft water by 

 heating it to boiling, and stirring. The wood thus treated, 

 when half dry, is brushed with a solution of one part, by 

 weight, of bicarbonate of potash in five parts of boiling wa- 

 ter, and is then allowed to dry thoroughly, and is to be 

 rubbed and polished as usual. Red beech and alder, under 

 this treatment, assume a most deceptive resemblance to 

 American walnut. The color is fixed in the wood to a 

 depth of one or two lines. 15 (7, XX., 1874, 313. 



OX PAIXT AS AX EXGIXEERIXG MATERIAL. 



In a paper on this subject read before the Society of Engi- 

 neers by Mr. Ernest Spon, the author remarked, in reference 

 to the composition and characteristics of the pigments usually 

 employed, that white-lead should be of good quality, and un- 

 mixed with such substances as chalk, sulphate of lead, and sul- 

 phate of baryta. Zinc white he considers not so objectionable 

 as white-lead, but proves to be dry under the brush and takes 

 longer in completely drying. Red-lead is durable and dries 

 well ; but antimony vermilion is capable of being substitut- 

 ed to advantage for red-lead. Black paints from the resid- 

 ual products of coal and shale-oil manufacture and oxide of 

 iron paints are generally used for iron work, for which pur- 

 pose they are peculiarly suited. He concludes, upon the 

 whole, that no better protection for iron-ore structures can 

 be had than oxide of iron paints. The real value, however, 

 of any paint depends upon the quality of the oil, the quality 

 of the pigment, and the care bestowed on the manufacture. 

 The superiority of most esteemed paints is due to this proc- 

 ess rather than to any process or material employed in the 

 preparation. Iro?i, May 8, 1875, 587. 



VARXISH FOR IMITATIXG GILDIXG OX BRASS AXD BROXZE. 



A beautiful imitation of gilding on brass and bronze articles 

 may be effected by means of a varnish composed of 160 grains 

 of gum lac, 40 grains of dragon's-blood, 10 grains of turmeric, 

 and 3320 grains of alcohol. The metal should be brushed 

 with the varnish, in all directions, by means of a sponge, and 

 then immediately warmed over a gentle charcoal fire. The 



