Document YrbLEn9eQbn7xXnv6M1yO1NrN

California Historical Society for reference use only EMI? g " May 12, 1908 I note you state that in making a teat ycfu a glass mortar ana pestle to intermingle the sine and color to he tested and thoroughly grind it together for son time and then weigh oat of this the desired amount, generally one B.e. for oil and one gram for water. Perhaps I do not just catch your idea. Is this method of testing used to show whether or not the color "bleeds"? If you use this method to determine strength of a color in oil or water. I should tHT.fr there would he great difficulty In insuring absolute accuracy* The method used in malting strength tsst "by the dry color houses here, is to first weigh out Zinc and place same on heavy plate of ground glass* 600 Then weigh out say SO M.G. of the positive color and place it in same pile with the zinc, then add a certain number of drops of oil (carefully counting the drops, so that tho aarne amount of oil shall be used for both lots of color to he tested), rub up the mass thoroughly with either a stiff palette knife or preferably a glass muller with ground bottom* We find vhis insures a very thorough mixing and approximates very closely conditions of colors that have been put through a regular mill. I suppose that in mentioning this, I am only repeating something with whiohydra are entirely familiar. If so, kindly pardon me* Very likely I misunderstood your remarks regarding your Mortar & Pestle test and that your tost refers