Improvements in Aniline Colors

1878 Scientific American  
SCIENTIFIC AMERICAN SUPPLEMENT, No_ 124. 1975 HOW GRANITE IS POLISHED. particularly old portraits, and bave in my time cleansed ; ber Zeitung, gives tbe following receipt: Dissolve 17).4 ozs. many bundreds. Tbe "lan wbicb I adopt is as folIows: I of solid extract of logwood in 525 fluid ozs. of water, and NOTIDNG more elegant is now employed in arcbitecture " I place tbem one or two at a time in a sballow disb add 387 grains of yellow cbromate of potasb, 17).4 ozs. alum, tban tbe polisbed
more » ... tbe polisbed granite pillars which adorn many of the and pour water o � er them until they ar � completely soake d �1� ozs. gum arab ic, and 17).4. o�s. su�ar-cand;v. �hen all trade palaces of Boston and other large cities. These pi!-0 1' saturated witb it. I then carefully pour off the water, IS <1lssolved, 17).4. ozs' . of murIatlc aCId are stlrred m drop lars always attract sucb attentionand admiration that it : and po ur on to the prints a solution of ch_oride of lime (1 by dro p. If the mk IS not to copy, the gum and sugar may not be uninteresting to describe briefly the method empart liq. calcis chlorate, B. P., to 39 parts of water). As a are omltted. ployed in polishing them. general rule, the stains disappear as if by magic, but occa-IMPROVEMENTS IN ANILINE BLACKS. The substances used in grinding and polishin� granite sionally they are obstinate. When that is the case I pour on shafts are beach sand and emery, applied in certam quantithe spot pure liq. calcis chlorate, and if that does not suc· tieR at a certain velocity of revolution for tbe column, as ceed, I add a little acid nitro . hydrochlor. dil. I have never the work is done in a lathe similaI' in so me respects to the had a print which has not succumbed to this treatment-in lathes for turning and polishing metals and woods, except fact, as a rule, they become too white. As soon as they are timt the spindIes both revolve, that in the foot·stock as weIl clean, they must be carefully washed with successive por· as that in the head·stock. The lathe is driven at different tions of water, until the wllole of the chlorine is got rid of. speeds to suit the diameter of the shaft to be ground and They should then be placed in a very weak solution of isin polished, for a uniform surface speed of two hundred and glass or glue, and many collectors color this solution with thirty to two hundred and forty revolutions per minute is coffee grounds, etc., to give a yellow tint to the print. They reqUlred for the work, and it is evident that while a shaft should be dried between folds of blotting paper either in a of tweive Inches diameter would have to revolve about press or under a heavy book, g, nd finally ironed with an or· seventy·seven times per minute, one of three feet diameter dinary flatiron to restore the gloss, etc. (place clean paper would reqUIre only one·third that rotary speed, or about between the iron and the print)." twenty·five turns. The centers of the columns are found on the ends by measurements, and proper boxes are secured into cavities PROCESSES FOR THE PREPARATION OF VIOLET made for the purpose, and tbe column IS then swung in tbe ULTRAMARINE. lathe. At the rear of the latoe, extendmg its entire length,
doi:10.1038/scientificamerican05181878-1975esupp fatcat:6p57vji6wbduzcuxygoinpaxbe